bitmath: Finish up optimizations
This patch adds support for other compilers and systems including MSVC, Intel C compiler etc.. Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
This commit is contained in:
Cristian Rodríguez
Erik de Castro Lopo
parent
605f920816
commit
387b72731d
@ -36,54 +36,6 @@
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#include "private/bitmath.h"
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#include "FLAC/assert.h"
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/* An example of what FLAC__bitmath_ilog2() computes:
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*
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* ilog2( 0) = assertion failure
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* ilog2( 1) = 0
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* ilog2( 2) = 1
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* ilog2( 3) = 1
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* ilog2( 4) = 2
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* ilog2( 5) = 2
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* ilog2( 6) = 2
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* ilog2( 7) = 2
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* ilog2( 8) = 3
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* ilog2( 9) = 3
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* ilog2(10) = 3
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* ilog2(11) = 3
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* ilog2(12) = 3
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* ilog2(13) = 3
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* ilog2(14) = 3
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* ilog2(15) = 3
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* ilog2(16) = 4
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* ilog2(17) = 4
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* ilog2(18) = 4
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*/
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#ifndef __GNUC__
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/* For GNUC, use static inline version in include/private/bitmath.h. */
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unsigned FLAC__bitmath_ilog2(FLAC__uint32 v)
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{
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unsigned l = 0;
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if (v == 0)
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return 0;
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while(v >>= 1)
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l++;
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return l;
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}
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unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v)
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{
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unsigned l = 0;
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if (v == 0)
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return 0;
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while(v >>= 1)
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l++;
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return l;
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}
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#endif
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/* An example of what FLAC__bitmath_silog2() computes:
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*
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* silog2(-10) = 5
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@ -43,7 +43,7 @@
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#include "share/endswap.h"
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/* Things should be fastest when this matches the machine word size */
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/* WATCHOUT: if you change this you must also change the following #defines down to COUNT_ZERO_MSBS below to match */
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/* WATCHOUT: if you change this you must also change the following #defines down to FLAC__clz_uint32 below to match */
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/* WATCHOUT: there are a few places where the code will not work unless uint32_t is >= 32 bits wide */
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/* also, some sections currently only have fast versions for 4 or 8 bytes per word */
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#define FLAC__BYTES_PER_WORD 4 /* sizeof uint32_t */
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@ -56,27 +56,6 @@
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#define SWAP_BE_WORD_TO_HOST(x) ENDSWAP_32(x)
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#endif
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#if defined(__GNUC__)
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/* "int __builtin_clz (unsigned int x) If x is 0, the result is undefined" */
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static inline uint32_t
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COUNT_ZERO_MSBS (uint32_t word)
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{
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if (word == 0)
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return 32;
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return __builtin_clz (word);
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}
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#else
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/* counts the # of zero MSBs in a word */
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#define COUNT_ZERO_MSBS(word) ( \
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(word) > 0xffffff ? byte_to_unary_table[(word) >> 24] : \
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!(word) ? 32 : \
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(word) > 0xffff ? byte_to_unary_table[(word) >> 16] + 8 : \
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(word) > 0xff ? byte_to_unary_table[(word) >> 8] + 16 : \
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byte_to_unary_table[(word)] + 24 \
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)
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#endif
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/*
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* This should be at least twice as large as the largest number of words
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* required to represent any 'number' (in any encoding) you are going to
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@ -93,25 +72,6 @@ COUNT_ZERO_MSBS (uint32_t word)
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*/
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static const unsigned FLAC__BITREADER_DEFAULT_CAPACITY = 65536u / FLAC__BITS_PER_WORD; /* in words */
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static const unsigned char byte_to_unary_table[] = {
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8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
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3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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};
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/* adjust for compilers that can't understand using LLU suffix for uint64_t literals */
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#ifdef _MSC_VER
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#define FLAC__U64L(x) x
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@ -679,7 +639,7 @@ FLAC__bool FLAC__bitreader_read_unary_unsigned(FLAC__BitReader *br, unsigned *va
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while(br->consumed_words < br->words) { /* if we've not consumed up to a partial tail word... */
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uint32_t b = br->buffer[br->consumed_words] << br->consumed_bits;
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if(b) {
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i = COUNT_ZERO_MSBS(b);
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i = FLAC__clz_uint32(b);
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*val += i;
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i++;
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br->consumed_bits += i;
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@ -709,7 +669,7 @@ FLAC__bool FLAC__bitreader_read_unary_unsigned(FLAC__BitReader *br, unsigned *va
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const unsigned end = br->bytes * 8;
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uint32_t b = (br->buffer[br->consumed_words] & (FLAC__WORD_ALL_ONES << (FLAC__BITS_PER_WORD-end))) << br->consumed_bits;
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if(b) {
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i = COUNT_ZERO_MSBS(b);
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i = FLAC__clz_uint32(b);
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*val += i;
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i++;
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br->consumed_bits += i;
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@ -800,7 +760,7 @@ FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[
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mov i, eax
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}
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#else
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i = COUNT_ZERO_MSBS(b);
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i = FLAC__clz_uint32(b);
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#endif
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uval += i;
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bits = parameter;
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@ -832,7 +792,7 @@ FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[
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const unsigned end = br->bytes * 8;
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uint32_t b = (br->buffer[cwords] & (FLAC__WORD_ALL_ONES << (FLAC__BITS_PER_WORD-end))) << cbits;
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if(b) {
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i = COUNT_ZERO_MSBS(b);
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i = FLAC__clz_uint32(b);
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uval += i;
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bits = parameter;
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i++;
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@ -984,7 +944,7 @@ break2:
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: "r"(b)
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);
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#else
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i = COUNT_ZERO_MSBS(b);
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i = FLAC__clz_uint32(b);
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#endif
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uval += i;
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cbits += i;
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@ -1015,7 +975,7 @@ break2:
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const unsigned end = br->bytes * 8;
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uint32_t b = (br->buffer[cwords] & ~(FLAC__WORD_ALL_ONES >> end)) << cbits;
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if(b) {
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i = COUNT_ZERO_MSBS(b);
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i = FLAC__clz_uint32(b);
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uval += i;
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cbits += i;
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cbits++; /* skip over stop bit */
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@ -34,28 +34,126 @@
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#include "FLAC/ordinals.h"
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/* for CHAR_BIT */
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#include <limits.h>
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#if defined(__GNUC__)
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#if defined(_MSC_VER) && (_MSC_VER >= 1400)
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#include <intrin.h> /* for _BitScanReverse* */
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#endif
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/* Will never be emitted for MSVC, GCC, Intel compilers */
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inline unsigned int FLAC__clz_soft_uint32(unsigned int word)
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{
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static const unsigned char byte_to_unary_table[] = {
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8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
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3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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};
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return (word) > 0xffffff ? byte_to_unary_table[(word) >> 24] :
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!(word) ? 32 :
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(word) > 0xffff ? byte_to_unary_table[(word) >> 16] + 8 :
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(word) > 0xff ? byte_to_unary_table[(word) >> 8] + 16 :
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byte_to_unary_table[(word)] + 24;
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}
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static inline unsigned int FLAC__clz_uint32(FLAC__uint32 v)
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{
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/* Never used with input 0 */
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#if defined(__INTEL_COMPILER)
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return _bit_scan_reverse(n) ^ 31U;
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#elif defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
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/* This will translate either to (bsr ^ 31U), clz , ctlz, cntlz, lzcnt depending on
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* -march= setting or to a software rutine in exotic machines. */
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return __builtin_clz(v);
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#elif defined(_MSC_VER) && (_MSC_VER >= 1400)
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FLAC__uint32 idx;
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_BitScanReverse(&idx, v);
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return idx ^ 31U;
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#else
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return FLAC__clz_soft_uint32(v);
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#endif
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}
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/* An example of what FLAC__bitmath_ilog2() computes:
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*
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* ilog2( 0) = undefined
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* ilog2( 1) = 0
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* ilog2( 2) = 1
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* ilog2( 3) = 1
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* ilog2( 4) = 2
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* ilog2( 5) = 2
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* ilog2( 6) = 2
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* ilog2( 7) = 2
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* ilog2( 8) = 3
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* ilog2( 9) = 3
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* ilog2(10) = 3
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* ilog2(11) = 3
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* ilog2(12) = 3
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* ilog2(13) = 3
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* ilog2(14) = 3
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* ilog2(15) = 3
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* ilog2(16) = 4
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* ilog2(17) = 4
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* ilog2(18) = 4
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*/
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static inline unsigned FLAC__bitmath_ilog2(FLAC__uint32 v)
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{
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if (v == 0)
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return 0;
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return sizeof(FLAC__uint32) * __CHAR_BIT__ - 1 - __builtin_clz(v);
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return sizeof(FLAC__uint32) * CHAR_BIT - 1 - FLAC__clz_uint32(v);
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}
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#ifdef FLAC__INTEGER_ONLY_LIBRARY /*Unused otherwise */
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static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v)
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{
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if (v == 0)
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return 0;
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return sizeof(FLAC__uint64) * __CHAR_BIT__ - 1 - __builtin_clzll(v);
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}
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#if && defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
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return sizeof(FLAC__uint64) * CHAR_BIT - 1 - __builtin_clzll(v);
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/* Sorry, only supported in win64/Itanium.. */
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#elif (defined(_MSC_VER) && (_MSC_VER >= 1400)) && (defined(_M_IA64) || defined(_WIN64))
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FLAC__uint64 idx;
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_BitScanReverse64(&idx, v);
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return idx ^ 63U;
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#else
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unsigned FLAC__bitmath_ilog2(FLAC__uint32 v);
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unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v);
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/* Brain-damaged compilers will use the fastest possible way that is,
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de Bruijn sequences (http://supertech.csail.mit.edu/papers/debruijn.pdf)
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(C) Timothy B. Terriberry (tterribe@xiph.org) 2001-2009 LGPL (v2 or later).
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*/
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static const unsigned char DEBRUIJN_IDX64[64]={
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0, 1, 2, 7, 3,13, 8,19, 4,25,14,28, 9,34,20,40,
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5,17,26,38,15,46,29,48,10,31,35,54,21,50,41,57,
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63, 6,12,18,24,27,33,39,16,37,45,47,30,53,49,56,
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62,11,23,32,36,44,52,55,61,22,43,51,60,42,59,58
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};
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int ret;
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ret= v>0;
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v|= v>>1;
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v|= v>>2;
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v|= v>>4;
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v|= v>>8;
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v|= v>>16;
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v|= v>>32;
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v= (v>>1)+1;
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ret+=DEBRUIJN_IDX64[v*0x218A392CD3D5DBF>>58&0x3F];
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return ret;
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#endif
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}
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#endif
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unsigned FLAC__bitmath_silog2(int v);
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