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	 463b3f0d7f
			
		
	
	
		463b3f0d7f
		
	
	
	
	
		
			
			Rename to parts$N_float_to_sint.  Reimplement
float128_to_int{32,64}{_round_to_zero} with FloatParts128.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
		
	
			
		
			
				
	
	
		
			818 lines
		
	
	
		
			22 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			818 lines
		
	
	
		
			22 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| /*
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|  * QEMU float support
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|  *
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|  * The code in this source file is derived from release 2a of the SoftFloat
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|  * IEC/IEEE Floating-point Arithmetic Package. Those parts of the code (and
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|  * some later contributions) are provided under that license, as detailed below.
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|  * It has subsequently been modified by contributors to the QEMU Project,
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|  * so some portions are provided under:
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|  *  the SoftFloat-2a license
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|  *  the BSD license
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|  *  GPL-v2-or-later
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|  *
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|  * Any future contributions to this file after December 1st 2014 will be
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|  * taken to be licensed under the Softfloat-2a license unless specifically
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|  * indicated otherwise.
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|  */
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| 
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| static void partsN(return_nan)(FloatPartsN *a, float_status *s)
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| {
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|     switch (a->cls) {
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|     case float_class_snan:
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|         float_raise(float_flag_invalid, s);
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|         if (s->default_nan_mode) {
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|             parts_default_nan(a, s);
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|         } else {
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|             parts_silence_nan(a, s);
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|         }
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|         break;
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|     case float_class_qnan:
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|         if (s->default_nan_mode) {
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|             parts_default_nan(a, s);
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|         }
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|         break;
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|     default:
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|         g_assert_not_reached();
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|     }
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| }
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| 
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| static FloatPartsN *partsN(pick_nan)(FloatPartsN *a, FloatPartsN *b,
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|                                      float_status *s)
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| {
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|     if (is_snan(a->cls) || is_snan(b->cls)) {
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|         float_raise(float_flag_invalid, s);
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|     }
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| 
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|     if (s->default_nan_mode) {
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|         parts_default_nan(a, s);
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|     } else {
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|         int cmp = frac_cmp(a, b);
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|         if (cmp == 0) {
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|             cmp = a->sign < b->sign;
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|         }
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| 
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|         if (pickNaN(a->cls, b->cls, cmp > 0, s)) {
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|             a = b;
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|         }
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|         if (is_snan(a->cls)) {
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|             parts_silence_nan(a, s);
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|         }
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|     }
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|     return a;
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| }
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| 
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| static FloatPartsN *partsN(pick_nan_muladd)(FloatPartsN *a, FloatPartsN *b,
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|                                             FloatPartsN *c, float_status *s,
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|                                             int ab_mask, int abc_mask)
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| {
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|     int which;
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| 
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|     if (unlikely(abc_mask & float_cmask_snan)) {
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|         float_raise(float_flag_invalid, s);
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|     }
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| 
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|     which = pickNaNMulAdd(a->cls, b->cls, c->cls,
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|                           ab_mask == float_cmask_infzero, s);
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| 
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|     if (s->default_nan_mode || which == 3) {
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|         /*
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|          * Note that this check is after pickNaNMulAdd so that function
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|          * has an opportunity to set the Invalid flag for infzero.
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|          */
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|         parts_default_nan(a, s);
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|         return a;
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|     }
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| 
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|     switch (which) {
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|     case 0:
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|         break;
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|     case 1:
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|         a = b;
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|         break;
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|     case 2:
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|         a = c;
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|         break;
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|     default:
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|         g_assert_not_reached();
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|     }
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|     if (is_snan(a->cls)) {
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|         parts_silence_nan(a, s);
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|     }
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|     return a;
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| }
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| 
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| /*
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|  * Canonicalize the FloatParts structure.  Determine the class,
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|  * unbias the exponent, and normalize the fraction.
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|  */
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| static void partsN(canonicalize)(FloatPartsN *p, float_status *status,
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|                                  const FloatFmt *fmt)
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| {
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|     if (unlikely(p->exp == 0)) {
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|         if (likely(frac_eqz(p))) {
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|             p->cls = float_class_zero;
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|         } else if (status->flush_inputs_to_zero) {
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|             float_raise(float_flag_input_denormal, status);
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|             p->cls = float_class_zero;
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|             frac_clear(p);
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|         } else {
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|             int shift = frac_normalize(p);
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|             p->cls = float_class_normal;
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|             p->exp = fmt->frac_shift - fmt->exp_bias - shift + 1;
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|         }
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|     } else if (likely(p->exp < fmt->exp_max) || fmt->arm_althp) {
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|         p->cls = float_class_normal;
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|         p->exp -= fmt->exp_bias;
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|         frac_shl(p, fmt->frac_shift);
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|         p->frac_hi |= DECOMPOSED_IMPLICIT_BIT;
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|     } else if (likely(frac_eqz(p))) {
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|         p->cls = float_class_inf;
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|     } else {
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|         frac_shl(p, fmt->frac_shift);
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|         p->cls = (parts_is_snan_frac(p->frac_hi, status)
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|                   ? float_class_snan : float_class_qnan);
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|     }
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| }
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| 
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| /*
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|  * Round and uncanonicalize a floating-point number by parts. There
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|  * are FRAC_SHIFT bits that may require rounding at the bottom of the
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|  * fraction; these bits will be removed. The exponent will be biased
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|  * by EXP_BIAS and must be bounded by [EXP_MAX-1, 0].
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|  */
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| static void partsN(uncanon)(FloatPartsN *p, float_status *s,
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|                             const FloatFmt *fmt)
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| {
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|     const int exp_max = fmt->exp_max;
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|     const int frac_shift = fmt->frac_shift;
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|     const uint64_t frac_lsb = fmt->frac_lsb;
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|     const uint64_t frac_lsbm1 = fmt->frac_lsbm1;
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|     const uint64_t round_mask = fmt->round_mask;
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|     const uint64_t roundeven_mask = fmt->roundeven_mask;
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|     uint64_t inc;
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|     bool overflow_norm;
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|     int exp, flags = 0;
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| 
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|     if (unlikely(p->cls != float_class_normal)) {
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|         switch (p->cls) {
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|         case float_class_zero:
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|             p->exp = 0;
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|             frac_clear(p);
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|             return;
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|         case float_class_inf:
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|             g_assert(!fmt->arm_althp);
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|             p->exp = fmt->exp_max;
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|             frac_clear(p);
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|             return;
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|         case float_class_qnan:
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|         case float_class_snan:
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|             g_assert(!fmt->arm_althp);
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|             p->exp = fmt->exp_max;
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|             frac_shr(p, fmt->frac_shift);
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|             return;
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|         default:
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|             break;
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|         }
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|         g_assert_not_reached();
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|     }
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| 
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|     switch (s->float_rounding_mode) {
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|     case float_round_nearest_even:
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|         overflow_norm = false;
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|         inc = ((p->frac_lo & roundeven_mask) != frac_lsbm1 ? frac_lsbm1 : 0);
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|         break;
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|     case float_round_ties_away:
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|         overflow_norm = false;
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|         inc = frac_lsbm1;
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|         break;
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|     case float_round_to_zero:
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|         overflow_norm = true;
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|         inc = 0;
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|         break;
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|     case float_round_up:
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|         inc = p->sign ? 0 : round_mask;
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|         overflow_norm = p->sign;
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|         break;
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|     case float_round_down:
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|         inc = p->sign ? round_mask : 0;
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|         overflow_norm = !p->sign;
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|         break;
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|     case float_round_to_odd:
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|         overflow_norm = true;
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|         inc = p->frac_lo & frac_lsb ? 0 : round_mask;
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|         break;
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|     default:
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|         g_assert_not_reached();
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|     }
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| 
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|     exp = p->exp + fmt->exp_bias;
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|     if (likely(exp > 0)) {
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|         if (p->frac_lo & round_mask) {
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|             flags |= float_flag_inexact;
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|             if (frac_addi(p, p, inc)) {
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|                 frac_shr(p, 1);
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|                 p->frac_hi |= DECOMPOSED_IMPLICIT_BIT;
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|                 exp++;
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|             }
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|         }
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|         frac_shr(p, frac_shift);
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| 
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|         if (fmt->arm_althp) {
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|             /* ARM Alt HP eschews Inf and NaN for a wider exponent.  */
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|             if (unlikely(exp > exp_max)) {
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|                 /* Overflow.  Return the maximum normal.  */
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|                 flags = float_flag_invalid;
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|                 exp = exp_max;
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|                 frac_allones(p);
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|             }
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|         } else if (unlikely(exp >= exp_max)) {
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|             flags |= float_flag_overflow | float_flag_inexact;
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|             if (overflow_norm) {
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|                 exp = exp_max - 1;
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|                 frac_allones(p);
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|             } else {
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|                 p->cls = float_class_inf;
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|                 exp = exp_max;
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|                 frac_clear(p);
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|             }
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|         }
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|     } else if (s->flush_to_zero) {
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|         flags |= float_flag_output_denormal;
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|         p->cls = float_class_zero;
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|         exp = 0;
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|         frac_clear(p);
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|     } else {
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|         bool is_tiny = s->tininess_before_rounding || exp < 0;
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| 
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|         if (!is_tiny) {
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|             FloatPartsN discard;
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|             is_tiny = !frac_addi(&discard, p, inc);
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|         }
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| 
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|         frac_shrjam(p, 1 - exp);
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| 
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|         if (p->frac_lo & round_mask) {
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|             /* Need to recompute round-to-even/round-to-odd. */
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|             switch (s->float_rounding_mode) {
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|             case float_round_nearest_even:
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|                 inc = ((p->frac_lo & roundeven_mask) != frac_lsbm1
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|                        ? frac_lsbm1 : 0);
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|                 break;
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|             case float_round_to_odd:
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|                 inc = p->frac_lo & frac_lsb ? 0 : round_mask;
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|                 break;
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|             default:
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|                 break;
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|             }
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|             flags |= float_flag_inexact;
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|             frac_addi(p, p, inc);
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|         }
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| 
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|         exp = (p->frac_hi & DECOMPOSED_IMPLICIT_BIT) != 0;
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|         frac_shr(p, frac_shift);
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| 
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|         if (is_tiny && (flags & float_flag_inexact)) {
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|             flags |= float_flag_underflow;
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|         }
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|         if (exp == 0 && frac_eqz(p)) {
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|             p->cls = float_class_zero;
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|         }
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|     }
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|     p->exp = exp;
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|     float_raise(flags, s);
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| }
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| 
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| /*
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|  * Returns the result of adding or subtracting the values of the
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|  * floating-point values `a' and `b'. The operation is performed
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|  * according to the IEC/IEEE Standard for Binary Floating-Point
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|  * Arithmetic.
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|  */
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| static FloatPartsN *partsN(addsub)(FloatPartsN *a, FloatPartsN *b,
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|                                    float_status *s, bool subtract)
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| {
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|     bool b_sign = b->sign ^ subtract;
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|     int ab_mask = float_cmask(a->cls) | float_cmask(b->cls);
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| 
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|     if (a->sign != b_sign) {
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|         /* Subtraction */
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|         if (likely(ab_mask == float_cmask_normal)) {
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|             if (parts_sub_normal(a, b)) {
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|                 return a;
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|             }
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|             /* Subtract was exact, fall through to set sign. */
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|             ab_mask = float_cmask_zero;
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|         }
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| 
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|         if (ab_mask == float_cmask_zero) {
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|             a->sign = s->float_rounding_mode == float_round_down;
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|             return a;
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|         }
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| 
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|         if (unlikely(ab_mask & float_cmask_anynan)) {
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|             goto p_nan;
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|         }
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| 
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|         if (ab_mask & float_cmask_inf) {
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|             if (a->cls != float_class_inf) {
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|                 /* N - Inf */
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|                 goto return_b;
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|             }
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|             if (b->cls != float_class_inf) {
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|                 /* Inf - N */
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|                 return a;
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|             }
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|             /* Inf - Inf */
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|             float_raise(float_flag_invalid, s);
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|             parts_default_nan(a, s);
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|             return a;
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|         }
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|     } else {
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|         /* Addition */
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|         if (likely(ab_mask == float_cmask_normal)) {
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|             parts_add_normal(a, b);
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|             return a;
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|         }
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| 
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|         if (ab_mask == float_cmask_zero) {
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|             return a;
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|         }
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| 
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|         if (unlikely(ab_mask & float_cmask_anynan)) {
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|             goto p_nan;
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|         }
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| 
 | |
|         if (ab_mask & float_cmask_inf) {
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|             a->cls = float_class_inf;
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|             return a;
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|         }
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|     }
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| 
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|     if (b->cls == float_class_zero) {
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|         g_assert(a->cls == float_class_normal);
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|         return a;
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|     }
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| 
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|     g_assert(a->cls == float_class_zero);
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|     g_assert(b->cls == float_class_normal);
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|  return_b:
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|     b->sign = b_sign;
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|     return b;
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| 
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|  p_nan:
 | |
|     return parts_pick_nan(a, b, s);
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| }
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| 
 | |
| /*
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|  * Returns the result of multiplying the floating-point values `a' and
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|  * `b'. The operation is performed according to the IEC/IEEE Standard
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|  * for Binary Floating-Point Arithmetic.
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|  */
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| static FloatPartsN *partsN(mul)(FloatPartsN *a, FloatPartsN *b,
 | |
|                                 float_status *s)
 | |
| {
 | |
|     int ab_mask = float_cmask(a->cls) | float_cmask(b->cls);
 | |
|     bool sign = a->sign ^ b->sign;
 | |
| 
 | |
|     if (likely(ab_mask == float_cmask_normal)) {
 | |
|         FloatPartsW tmp;
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| 
 | |
|         frac_mulw(&tmp, a, b);
 | |
|         frac_truncjam(a, &tmp);
 | |
| 
 | |
|         a->exp += b->exp + 1;
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|         if (!(a->frac_hi & DECOMPOSED_IMPLICIT_BIT)) {
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|             frac_add(a, a, a);
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|             a->exp -= 1;
 | |
|         }
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| 
 | |
|         a->sign = sign;
 | |
|         return a;
 | |
|     }
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| 
 | |
|     /* Inf * Zero == NaN */
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|     if (unlikely(ab_mask == float_cmask_infzero)) {
 | |
|         float_raise(float_flag_invalid, s);
 | |
|         parts_default_nan(a, s);
 | |
|         return a;
 | |
|     }
 | |
| 
 | |
|     if (unlikely(ab_mask & float_cmask_anynan)) {
 | |
|         return parts_pick_nan(a, b, s);
 | |
|     }
 | |
| 
 | |
|     /* Multiply by 0 or Inf */
 | |
|     if (ab_mask & float_cmask_inf) {
 | |
|         a->cls = float_class_inf;
 | |
|         a->sign = sign;
 | |
|         return a;
 | |
|     }
 | |
| 
 | |
|     g_assert(ab_mask & float_cmask_zero);
 | |
|     a->cls = float_class_zero;
 | |
|     a->sign = sign;
 | |
|     return a;
 | |
| }
 | |
| 
 | |
| /*
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|  * Returns the result of multiplying the floating-point values `a' and
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|  * `b' then adding 'c', with no intermediate rounding step after the
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|  * multiplication. The operation is performed according to the
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|  * IEC/IEEE Standard for Binary Floating-Point Arithmetic 754-2008.
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|  * The flags argument allows the caller to select negation of the
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|  * addend, the intermediate product, or the final result. (The
 | |
|  * difference between this and having the caller do a separate
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|  * negation is that negating externally will flip the sign bit on NaNs.)
 | |
|  *
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|  * Requires A and C extracted into a double-sized structure to provide the
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|  * extra space for the widening multiply.
 | |
|  */
 | |
| static FloatPartsN *partsN(muladd)(FloatPartsN *a, FloatPartsN *b,
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|                                    FloatPartsN *c, int flags, float_status *s)
 | |
| {
 | |
|     int ab_mask, abc_mask;
 | |
|     FloatPartsW p_widen, c_widen;
 | |
| 
 | |
|     ab_mask = float_cmask(a->cls) | float_cmask(b->cls);
 | |
|     abc_mask = float_cmask(c->cls) | ab_mask;
 | |
| 
 | |
|     /*
 | |
|      * It is implementation-defined whether the cases of (0,inf,qnan)
 | |
|      * and (inf,0,qnan) raise InvalidOperation or not (and what QNaN
 | |
|      * they return if they do), so we have to hand this information
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|      * off to the target-specific pick-a-NaN routine.
 | |
|      */
 | |
|     if (unlikely(abc_mask & float_cmask_anynan)) {
 | |
|         return parts_pick_nan_muladd(a, b, c, s, ab_mask, abc_mask);
 | |
|     }
 | |
| 
 | |
|     if (flags & float_muladd_negate_c) {
 | |
|         c->sign ^= 1;
 | |
|     }
 | |
| 
 | |
|     /* Compute the sign of the product into A. */
 | |
|     a->sign ^= b->sign;
 | |
|     if (flags & float_muladd_negate_product) {
 | |
|         a->sign ^= 1;
 | |
|     }
 | |
| 
 | |
|     if (unlikely(ab_mask != float_cmask_normal)) {
 | |
|         if (unlikely(ab_mask == float_cmask_infzero)) {
 | |
|             goto d_nan;
 | |
|         }
 | |
| 
 | |
|         if (ab_mask & float_cmask_inf) {
 | |
|             if (c->cls == float_class_inf && a->sign != c->sign) {
 | |
|                 goto d_nan;
 | |
|             }
 | |
|             goto return_inf;
 | |
|         }
 | |
| 
 | |
|         g_assert(ab_mask & float_cmask_zero);
 | |
|         if (c->cls == float_class_normal) {
 | |
|             *a = *c;
 | |
|             goto return_normal;
 | |
|         }
 | |
|         if (c->cls == float_class_zero) {
 | |
|             if (a->sign != c->sign) {
 | |
|                 goto return_sub_zero;
 | |
|             }
 | |
|             goto return_zero;
 | |
|         }
 | |
|         g_assert(c->cls == float_class_inf);
 | |
|     }
 | |
| 
 | |
|     if (unlikely(c->cls == float_class_inf)) {
 | |
|         a->sign = c->sign;
 | |
|         goto return_inf;
 | |
|     }
 | |
| 
 | |
|     /* Perform the multiplication step. */
 | |
|     p_widen.sign = a->sign;
 | |
|     p_widen.exp = a->exp + b->exp + 1;
 | |
|     frac_mulw(&p_widen, a, b);
 | |
|     if (!(p_widen.frac_hi & DECOMPOSED_IMPLICIT_BIT)) {
 | |
|         frac_add(&p_widen, &p_widen, &p_widen);
 | |
|         p_widen.exp -= 1;
 | |
|     }
 | |
| 
 | |
|     /* Perform the addition step. */
 | |
|     if (c->cls != float_class_zero) {
 | |
|         /* Zero-extend C to less significant bits. */
 | |
|         frac_widen(&c_widen, c);
 | |
|         c_widen.exp = c->exp;
 | |
| 
 | |
|         if (a->sign == c->sign) {
 | |
|             parts_add_normal(&p_widen, &c_widen);
 | |
|         } else if (!parts_sub_normal(&p_widen, &c_widen)) {
 | |
|             goto return_sub_zero;
 | |
|         }
 | |
|     }
 | |
| 
 | |
|     /* Narrow with sticky bit, for proper rounding later. */
 | |
|     frac_truncjam(a, &p_widen);
 | |
|     a->sign = p_widen.sign;
 | |
|     a->exp = p_widen.exp;
 | |
| 
 | |
|  return_normal:
 | |
|     if (flags & float_muladd_halve_result) {
 | |
|         a->exp -= 1;
 | |
|     }
 | |
|  finish_sign:
 | |
|     if (flags & float_muladd_negate_result) {
 | |
|         a->sign ^= 1;
 | |
|     }
 | |
|     return a;
 | |
| 
 | |
|  return_sub_zero:
 | |
|     a->sign = s->float_rounding_mode == float_round_down;
 | |
|  return_zero:
 | |
|     a->cls = float_class_zero;
 | |
|     goto finish_sign;
 | |
| 
 | |
|  return_inf:
 | |
|     a->cls = float_class_inf;
 | |
|     goto finish_sign;
 | |
| 
 | |
|  d_nan:
 | |
|     float_raise(float_flag_invalid, s);
 | |
|     parts_default_nan(a, s);
 | |
|     return a;
 | |
| }
 | |
| 
 | |
| /*
 | |
|  * Returns the result of dividing the floating-point value `a' by the
 | |
|  * corresponding value `b'. The operation is performed according to
 | |
|  * the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 | |
|  */
 | |
| static FloatPartsN *partsN(div)(FloatPartsN *a, FloatPartsN *b,
 | |
|                                 float_status *s)
 | |
| {
 | |
|     int ab_mask = float_cmask(a->cls) | float_cmask(b->cls);
 | |
|     bool sign = a->sign ^ b->sign;
 | |
| 
 | |
|     if (likely(ab_mask == float_cmask_normal)) {
 | |
|         a->sign = sign;
 | |
|         a->exp -= b->exp + frac_div(a, b);
 | |
|         return a;
 | |
|     }
 | |
| 
 | |
|     /* 0/0 or Inf/Inf => NaN */
 | |
|     if (unlikely(ab_mask == float_cmask_zero) ||
 | |
|         unlikely(ab_mask == float_cmask_inf)) {
 | |
|         float_raise(float_flag_invalid, s);
 | |
|         parts_default_nan(a, s);
 | |
|         return a;
 | |
|     }
 | |
| 
 | |
|     /* All the NaN cases */
 | |
|     if (unlikely(ab_mask & float_cmask_anynan)) {
 | |
|         return parts_pick_nan(a, b, s);
 | |
|     }
 | |
| 
 | |
|     a->sign = sign;
 | |
| 
 | |
|     /* Inf / X */
 | |
|     if (a->cls == float_class_inf) {
 | |
|         return a;
 | |
|     }
 | |
| 
 | |
|     /* 0 / X */
 | |
|     if (a->cls == float_class_zero) {
 | |
|         return a;
 | |
|     }
 | |
| 
 | |
|     /* X / Inf */
 | |
|     if (b->cls == float_class_inf) {
 | |
|         a->cls = float_class_zero;
 | |
|         return a;
 | |
|     }
 | |
| 
 | |
|     /* X / 0 => Inf */
 | |
|     g_assert(b->cls == float_class_zero);
 | |
|     float_raise(float_flag_divbyzero, s);
 | |
|     a->cls = float_class_inf;
 | |
|     return a;
 | |
| }
 | |
| 
 | |
| /*
 | |
|  * Rounds the floating-point value `a' to an integer, and returns the
 | |
|  * result as a floating-point value. The operation is performed
 | |
|  * according to the IEC/IEEE Standard for Binary Floating-Point
 | |
|  * Arithmetic.
 | |
|  *
 | |
|  * parts_round_to_int_normal is an internal helper function for
 | |
|  * normal numbers only, returning true for inexact but not directly
 | |
|  * raising float_flag_inexact.
 | |
|  */
 | |
| static bool partsN(round_to_int_normal)(FloatPartsN *a, FloatRoundMode rmode,
 | |
|                                         int scale, int frac_size)
 | |
| {
 | |
|     uint64_t frac_lsb, frac_lsbm1, rnd_even_mask, rnd_mask, inc;
 | |
|     int shift_adj;
 | |
| 
 | |
|     scale = MIN(MAX(scale, -0x10000), 0x10000);
 | |
|     a->exp += scale;
 | |
| 
 | |
|     if (a->exp < 0) {
 | |
|         bool one;
 | |
| 
 | |
|         /* All fractional */
 | |
|         switch (rmode) {
 | |
|         case float_round_nearest_even:
 | |
|             one = false;
 | |
|             if (a->exp == -1) {
 | |
|                 FloatPartsN tmp;
 | |
|                 /* Shift left one, discarding DECOMPOSED_IMPLICIT_BIT */
 | |
|                 frac_add(&tmp, a, a);
 | |
|                 /* Anything remaining means frac > 0.5. */
 | |
|                 one = !frac_eqz(&tmp);
 | |
|             }
 | |
|             break;
 | |
|         case float_round_ties_away:
 | |
|             one = a->exp == -1;
 | |
|             break;
 | |
|         case float_round_to_zero:
 | |
|             one = false;
 | |
|             break;
 | |
|         case float_round_up:
 | |
|             one = !a->sign;
 | |
|             break;
 | |
|         case float_round_down:
 | |
|             one = a->sign;
 | |
|             break;
 | |
|         case float_round_to_odd:
 | |
|             one = true;
 | |
|             break;
 | |
|         default:
 | |
|             g_assert_not_reached();
 | |
|         }
 | |
| 
 | |
|         frac_clear(a);
 | |
|         a->exp = 0;
 | |
|         if (one) {
 | |
|             a->frac_hi = DECOMPOSED_IMPLICIT_BIT;
 | |
|         } else {
 | |
|             a->cls = float_class_zero;
 | |
|         }
 | |
|         return true;
 | |
|     }
 | |
| 
 | |
|     if (a->exp >= frac_size) {
 | |
|         /* All integral */
 | |
|         return false;
 | |
|     }
 | |
| 
 | |
|     if (N > 64 && a->exp < N - 64) {
 | |
|         /*
 | |
|          * Rounding is not in the low word -- shift lsb to bit 2,
 | |
|          * which leaves room for sticky and rounding bit.
 | |
|          */
 | |
|         shift_adj = (N - 1) - (a->exp + 2);
 | |
|         frac_shrjam(a, shift_adj);
 | |
|         frac_lsb = 1 << 2;
 | |
|     } else {
 | |
|         shift_adj = 0;
 | |
|         frac_lsb = DECOMPOSED_IMPLICIT_BIT >> (a->exp & 63);
 | |
|     }
 | |
| 
 | |
|     frac_lsbm1 = frac_lsb >> 1;
 | |
|     rnd_mask = frac_lsb - 1;
 | |
|     rnd_even_mask = rnd_mask | frac_lsb;
 | |
| 
 | |
|     if (!(a->frac_lo & rnd_mask)) {
 | |
|         /* Fractional bits already clear, undo the shift above. */
 | |
|         frac_shl(a, shift_adj);
 | |
|         return false;
 | |
|     }
 | |
| 
 | |
|     switch (rmode) {
 | |
|     case float_round_nearest_even:
 | |
|         inc = ((a->frac_lo & rnd_even_mask) != frac_lsbm1 ? frac_lsbm1 : 0);
 | |
|         break;
 | |
|     case float_round_ties_away:
 | |
|         inc = frac_lsbm1;
 | |
|         break;
 | |
|     case float_round_to_zero:
 | |
|         inc = 0;
 | |
|         break;
 | |
|     case float_round_up:
 | |
|         inc = a->sign ? 0 : rnd_mask;
 | |
|         break;
 | |
|     case float_round_down:
 | |
|         inc = a->sign ? rnd_mask : 0;
 | |
|         break;
 | |
|     case float_round_to_odd:
 | |
|         inc = a->frac_lo & frac_lsb ? 0 : rnd_mask;
 | |
|         break;
 | |
|     default:
 | |
|         g_assert_not_reached();
 | |
|     }
 | |
| 
 | |
|     if (shift_adj == 0) {
 | |
|         if (frac_addi(a, a, inc)) {
 | |
|             frac_shr(a, 1);
 | |
|             a->frac_hi |= DECOMPOSED_IMPLICIT_BIT;
 | |
|             a->exp++;
 | |
|         }
 | |
|         a->frac_lo &= ~rnd_mask;
 | |
|     } else {
 | |
|         frac_addi(a, a, inc);
 | |
|         a->frac_lo &= ~rnd_mask;
 | |
|         /* Be careful shifting back, not to overflow */
 | |
|         frac_shl(a, shift_adj - 1);
 | |
|         if (a->frac_hi & DECOMPOSED_IMPLICIT_BIT) {
 | |
|             a->exp++;
 | |
|         } else {
 | |
|             frac_add(a, a, a);
 | |
|         }
 | |
|     }
 | |
|     return true;
 | |
| }
 | |
| 
 | |
| static void partsN(round_to_int)(FloatPartsN *a, FloatRoundMode rmode,
 | |
|                                  int scale, float_status *s,
 | |
|                                  const FloatFmt *fmt)
 | |
| {
 | |
|     switch (a->cls) {
 | |
|     case float_class_qnan:
 | |
|     case float_class_snan:
 | |
|         parts_return_nan(a, s);
 | |
|         break;
 | |
|     case float_class_zero:
 | |
|     case float_class_inf:
 | |
|         break;
 | |
|     case float_class_normal:
 | |
|         if (parts_round_to_int_normal(a, rmode, scale, fmt->frac_size)) {
 | |
|             float_raise(float_flag_inexact, s);
 | |
|         }
 | |
|         break;
 | |
|     default:
 | |
|         g_assert_not_reached();
 | |
|     }
 | |
| }
 | |
| 
 | |
| /*
 | |
|  * Returns the result of converting the floating-point value `a' to
 | |
|  * the two's complement integer format. The conversion is performed
 | |
|  * according to the IEC/IEEE Standard for Binary Floating-Point
 | |
|  * Arithmetic---which means in particular that the conversion is
 | |
|  * rounded according to the current rounding mode. If `a' is a NaN,
 | |
|  * the largest positive integer is returned. Otherwise, if the
 | |
|  * conversion overflows, the largest integer with the same sign as `a'
 | |
|  * is returned.
 | |
| */
 | |
| static int64_t partsN(float_to_sint)(FloatPartsN *p, FloatRoundMode rmode,
 | |
|                                      int scale, int64_t min, int64_t max,
 | |
|                                      float_status *s)
 | |
| {
 | |
|     int flags = 0;
 | |
|     uint64_t r;
 | |
| 
 | |
|     switch (p->cls) {
 | |
|     case float_class_snan:
 | |
|     case float_class_qnan:
 | |
|         flags = float_flag_invalid;
 | |
|         r = max;
 | |
|         break;
 | |
| 
 | |
|     case float_class_inf:
 | |
|         flags = float_flag_invalid;
 | |
|         r = p->sign ? min : max;
 | |
|         break;
 | |
| 
 | |
|     case float_class_zero:
 | |
|         return 0;
 | |
| 
 | |
|     case float_class_normal:
 | |
|         /* TODO: N - 2 is frac_size for rounding; could use input fmt. */
 | |
|         if (parts_round_to_int_normal(p, rmode, scale, N - 2)) {
 | |
|             flags = float_flag_inexact;
 | |
|         }
 | |
| 
 | |
|         if (p->exp <= DECOMPOSED_BINARY_POINT) {
 | |
|             r = p->frac_hi >> (DECOMPOSED_BINARY_POINT - p->exp);
 | |
|         } else {
 | |
|             r = UINT64_MAX;
 | |
|         }
 | |
|         if (p->sign) {
 | |
|             if (r <= -(uint64_t)min) {
 | |
|                 r = -r;
 | |
|             } else {
 | |
|                 flags = float_flag_invalid;
 | |
|                 r = min;
 | |
|             }
 | |
|         } else if (r > max) {
 | |
|             flags = float_flag_invalid;
 | |
|             r = max;
 | |
|         }
 | |
|         break;
 | |
| 
 | |
|     default:
 | |
|         g_assert_not_reached();
 | |
|     }
 | |
| 
 | |
|     float_raise(flags, s);
 | |
|     return r;
 | |
| }
 |