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>
diff --git a/src/libFLAC/bitreader.c b/src/libFLAC/bitreader.c
index dcd9e42..9e15db0 100644
--- a/src/libFLAC/bitreader.c
+++ b/src/libFLAC/bitreader.c
@@ -43,7 +43,7 @@
#include "share/endswap.h"
/* Things should be fastest when this matches the machine word size */
-/* WATCHOUT: if you change this you must also change the following #defines down to COUNT_ZERO_MSBS below to match */
+/* WATCHOUT: if you change this you must also change the following #defines down to FLAC__clz_uint32 below to match */
/* WATCHOUT: there are a few places where the code will not work unless uint32_t is >= 32 bits wide */
/* also, some sections currently only have fast versions for 4 or 8 bytes per word */
#define FLAC__BYTES_PER_WORD 4 /* sizeof uint32_t */
@@ -56,27 +56,6 @@
#define SWAP_BE_WORD_TO_HOST(x) ENDSWAP_32(x)
#endif
-#if defined(__GNUC__)
-/* "int __builtin_clz (unsigned int x) If x is 0, the result is undefined" */
-static inline uint32_t
-COUNT_ZERO_MSBS (uint32_t word)
-{
- if (word == 0)
- return 32;
- return __builtin_clz (word);
-}
-#else
-/* counts the # of zero MSBs in a word */
-#define COUNT_ZERO_MSBS(word) ( \
- (word) > 0xffffff ? byte_to_unary_table[(word) >> 24] : \
- !(word) ? 32 : \
- (word) > 0xffff ? byte_to_unary_table[(word) >> 16] + 8 : \
- (word) > 0xff ? byte_to_unary_table[(word) >> 8] + 16 : \
- byte_to_unary_table[(word)] + 24 \
-)
-#endif
-
-
/*
* This should be at least twice as large as the largest number of words
* required to represent any 'number' (in any encoding) you are going to
@@ -93,25 +72,6 @@
*/
static const unsigned FLAC__BITREADER_DEFAULT_CAPACITY = 65536u / FLAC__BITS_PER_WORD; /* in words */
-static const unsigned char byte_to_unary_table[] = {
- 8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
- 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
- 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
- 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
- 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
- 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
- 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
- 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
-};
-
/* adjust for compilers that can't understand using LLU suffix for uint64_t literals */
#ifdef _MSC_VER
#define FLAC__U64L(x) x
@@ -679,7 +639,7 @@
while(br->consumed_words < br->words) { /* if we've not consumed up to a partial tail word... */
uint32_t b = br->buffer[br->consumed_words] << br->consumed_bits;
if(b) {
- i = COUNT_ZERO_MSBS(b);
+ i = FLAC__clz_uint32(b);
*val += i;
i++;
br->consumed_bits += i;
@@ -709,7 +669,7 @@
const unsigned end = br->bytes * 8;
uint32_t b = (br->buffer[br->consumed_words] & (FLAC__WORD_ALL_ONES << (FLAC__BITS_PER_WORD-end))) << br->consumed_bits;
if(b) {
- i = COUNT_ZERO_MSBS(b);
+ i = FLAC__clz_uint32(b);
*val += i;
i++;
br->consumed_bits += i;
@@ -800,7 +760,7 @@
mov i, eax
}
#else
- i = COUNT_ZERO_MSBS(b);
+ i = FLAC__clz_uint32(b);
#endif
uval += i;
bits = parameter;
@@ -832,7 +792,7 @@
const unsigned end = br->bytes * 8;
uint32_t b = (br->buffer[cwords] & (FLAC__WORD_ALL_ONES << (FLAC__BITS_PER_WORD-end))) << cbits;
if(b) {
- i = COUNT_ZERO_MSBS(b);
+ i = FLAC__clz_uint32(b);
uval += i;
bits = parameter;
i++;
@@ -984,7 +944,7 @@
: "r"(b)
);
#else
- i = COUNT_ZERO_MSBS(b);
+ i = FLAC__clz_uint32(b);
#endif
uval += i;
cbits += i;
@@ -1015,7 +975,7 @@
const unsigned end = br->bytes * 8;
uint32_t b = (br->buffer[cwords] & ~(FLAC__WORD_ALL_ONES >> end)) << cbits;
if(b) {
- i = COUNT_ZERO_MSBS(b);
+ i = FLAC__clz_uint32(b);
uval += i;
cbits += i;
cbits++; /* skip over stop bit */