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quic: precompute golomb codes

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We can avoid repetitive computation by using two precomputed array, of
8k each.

before:
     1.79%  lt-spicy-stats  libspice-client-glib-2.0.so.8.4.0  [.]
     golomb_code_len_8bpc

after:
     0.79%  lt-spicy-stats  libspice-client-glib-2.0.so.8.4.0  [.]
     golomb_code_len_8bpc
This commit is contained in:
Marc-André Lureau 2013-09-08 21:04:49 +02:00 committed by Marc-André Lureau
parent 8db88d2854
commit 4857653686
2 changed files with 34 additions and 15 deletions
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25
common/quic.c
View File

@ -75,6 +75,9 @@ typedef struct QuicFamily {
unsigned int notGRsuffixlen[MAXNUMCODES]; /* indexed by code number, contains suffix
length of the not-GR codeword */
unsigned int golomb_code_len[256][MAXNUMCODES];
unsigned int golomb_code[256][MAXNUMCODES];
/* array for translating distribution U to L for depths up to 8 bpp,
initialized by decorelateinit() */
BYTE xlatU2L[256];
@ -360,9 +363,22 @@ static void corelate_init(QuicFamily *family, int bpc)
}
}
static void golomb_coding_slow(QuicFamily *family, const BYTE n, const unsigned int l,
unsigned int * const codeword,
unsigned int * const codewordlen)
{
if (n < family->nGRcodewords[l]) {
(*codeword) = bitat[l] | (n & bppmask[l]);
(*codewordlen) = (n >> l) + l + 1;
} else {
(*codeword) = n - family->nGRcodewords[l];
(*codewordlen) = family->notGRcwlen[l];
}
}
static void family_init(QuicFamily *family, int bpc, int limit)
{
int l;
int l, b;
for (l = 0; l < bpc; l++) { /* fill arrays indexed by code number */
int altprefixlen, altcodewords;
@ -378,6 +394,13 @@ static void family_init(QuicFamily *family, int bpc, int limit)
family->notGRcwlen[l] = altprefixlen + ceil_log_2(altcodewords);
family->notGRprefixmask[l] = bppmask[32 - altprefixlen]; /* needed for decoding only */
family->notGRsuffixlen[l] = ceil_log_2(altcodewords); /* needed for decoding only */
for (b = 0; b < 256; b++) {
unsigned int code, len;
golomb_coding_slow(family, b, l, &code, &len);
family->golomb_code[b][l] = code;
family->golomb_code_len[b][l] = len;
}
}
decorelate_init(family, bpc);

24
common/quic_family_tmpl.c
View File

@ -34,26 +34,21 @@
#define BPC 5
#endif
static unsigned int FNAME(golomb_code_len)(const BYTE n, const unsigned int l)
static inline unsigned int FNAME(golomb_code)(const BYTE n, const unsigned int l)
{
if (n < VNAME(family).nGRcodewords[l]) {
return (n >> l) + 1 + l;
} else {
return VNAME(family).notGRcwlen[l];
}
return VNAME(family).golomb_code[n][l];
}
static inline unsigned int FNAME(golomb_code_len)(const BYTE n, const unsigned int l)
{
return VNAME(family).golomb_code_len[n][l];
}
static void FNAME(golomb_coding)(const BYTE n, const unsigned int l, unsigned int * const codeword,
unsigned int * const codewordlen)
{
if (n < VNAME(family).nGRcodewords[l]) {
(*codeword) = bitat[l] | (n & bppmask[l]);
(*codewordlen) = (n >> l) + l + 1;
} else {
(*codeword) = n - VNAME(family).nGRcodewords[l];
(*codewordlen) = VNAME(family).notGRcwlen[l];
}
*codeword = FNAME(golomb_code)(n, l);
*codewordlen = FNAME(golomb_code_len)(n, l);
}
static unsigned int FNAME(golomb_decoding)(const unsigned int l, const unsigned int bits,
@ -76,6 +71,7 @@ static unsigned int FNAME(golomb_decoding)(const unsigned int l, const unsigned
static void FNAME(update_model)(CommonState *state, s_bucket * const bucket,
const BYTE curval)
{
spice_static_assert(BPC >= 1);
const unsigned int bpp = BPC;
COUNTER * const pcounters = bucket->pcounters;
unsigned int i;