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BitTrace: if BITTRACE is > 0, record and print syntax bits used

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* Bittrace decoding is ~3x slower.
* Binary is the same byte-wise if BITTRACE=0
* Example output:
=== Bit traces ===
global-header    :    174 bytes   	[ 0.69%] [count:    1850]
segments         :    246 bytes   	[ 0.98%] [count:    3072]
block-size       :    170 bytes   	[ 0.68%] [count:    1536]
pred-modes       :   3829 bytes   	[15.27%] [count:   51458]
pred-modes-uv    :    279 bytes   	[ 1.11%] [count:    2329]
coeffs           :  20370 bytes   	[81.27%] [count:  212914]
Total: 25065 bytes

Change-Id: Ie32569c4e54a7ec13264e68d2dae2ce45c8536cb
This commit is contained in:
Pascal Massimino
2019-03-12 09:48:37 +01:00
parent 067031eaed
commit fcfd9c71b4
7 changed files with 203 additions and 86 deletions
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11
src/utils/bit_reader_inl_utils.h
View File

@ -104,7 +104,8 @@ void VP8LoadNewBytes(VP8BitReader* const br) {
}
// Read a bit with proba 'prob'. Speed-critical function!
static WEBP_INLINE int VP8GetBit(VP8BitReader* const br, int prob) {
static WEBP_INLINE int VP8GetBit(VP8BitReader* const br,
int prob, const char label[]) {
// Don't move this declaration! It makes a big speed difference to store
// 'range' *before* calling VP8LoadNewBytes(), even if this function doesn't
// alter br->range_ value.
@ -129,13 +130,14 @@ static WEBP_INLINE int VP8GetBit(VP8BitReader* const br, int prob) {
br->bits_ -= shift;
}
br->range_ = range - 1;
BT_TRACK(br);
return bit;
}
}
// simplified version of VP8GetBit() for prob=0x80 (note shift is always 1 here)
static WEBP_UBSAN_IGNORE_UNSIGNED_OVERFLOW WEBP_INLINE
int VP8GetSigned(VP8BitReader* const br, int v) {
int VP8GetSigned(VP8BitReader* const br, int v, const char label[]) {
if (br->bits_ < 0) {
VP8LoadNewBytes(br);
}
@ -148,11 +150,13 @@ int VP8GetSigned(VP8BitReader* const br, int v) {
br->range_ += mask;
br->range_ |= 1;
br->value_ -= (bit_t)((split + 1) & mask) << pos;
BT_TRACK(br);
return (v ^ mask) - mask;
}
}
static WEBP_INLINE int VP8GetBitAlt(VP8BitReader* const br, int prob) {
static WEBP_INLINE int VP8GetBitAlt(VP8BitReader* const br,
int prob, const char label[]) {
// Don't move this declaration! It makes a big speed difference to store
// 'range' *before* calling VP8LoadNewBytes(), even if this function doesn't
// alter br->range_ value.
@ -179,6 +183,7 @@ static WEBP_INLINE int VP8GetBitAlt(VP8BitReader* const br, int prob) {
br->bits_ -= shift;
}
br->range_ = range;
BT_TRACK(br);
return bit;
}
}

86
src/utils/bit_reader_utils.c
View File

@ -102,17 +102,18 @@ void VP8LoadFinalBytes(VP8BitReader* const br) {
//------------------------------------------------------------------------------
// Higher-level calls
uint32_t VP8GetValue(VP8BitReader* const br, int bits) {
uint32_t VP8GetValue(VP8BitReader* const br, int bits, const char label[]) {
uint32_t v = 0;
while (bits-- > 0) {
v |= VP8GetBit(br, 0x80) << bits;
v |= VP8GetBit(br, 0x80, label) << bits;
}
return v;
}
int32_t VP8GetSignedValue(VP8BitReader* const br, int bits) {
const int value = VP8GetValue(br, bits);
return VP8Get(br) ? -value : value;
int32_t VP8GetSignedValue(VP8BitReader* const br, int bits,
const char label[]) {
const int value = VP8GetValue(br, bits, label);
return VP8Get(br, label) ? -value : value;
}
//------------------------------------------------------------------------------
@ -220,3 +221,78 @@ uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) {
}
//------------------------------------------------------------------------------
// Bit-tracing tool
#if (BITTRACE > 0)
#include <stdlib.h> // for atexit()
#include <stdio.h>
#include <string.h>
#define MAX_NUM_LABELS 32
static struct {
const char* label;
int size;
int count;
} kLabels[MAX_NUM_LABELS];
static int last_label = 0;
static int last_pos = 0;
static const uint8_t* buf_start = NULL;
static int init_done = 0;
static void PrintBitTraces(void) {
int i;
int scale = 1;
int total = 0;
const char* units = "bits";
#if (BITTRACE == 2)
scale = 8;
units = "bytes";
#endif
for (i = 0; i < last_label; ++i) total += kLabels[i].size;
if (total < 1) total = 1; // avoid rounding errors
printf("=== Bit traces ===\n");
for (i = 0; i < last_label; ++i) {
const int skip = 16 - (int)strlen(kLabels[i].label);
const int value = (kLabels[i].size + scale - 1) / scale;
assert(skip > 0);
printf("%s \%*s: %6d %s \t[%5.2f%%] [count: %7d]\n",
kLabels[i].label, skip, "", value, units,
100.f * kLabels[i].size / total,
kLabels[i].count);
}
total = (total + scale - 1) / scale;
printf("Total: %d %s\n", total, units);
}
void BitTrace(const struct VP8BitReader* const br, const char label[]) {
int i, pos;
if (!init_done) {
memset(kLabels, 0, sizeof(kLabels));
atexit(PrintBitTraces);
buf_start = br->buf_;
init_done = 1;
}
pos = (int)(br->buf_ - buf_start) * 8 - br->bits_;
// if there's a too large jump, we've changed partition -> reset counter
if (abs(pos - last_pos) > 32) {
buf_start = br->buf_;
pos = 0;
last_pos = 0;
}
if (br->range_ >= 0x7f) pos += kVP8Log2Range[br->range_ - 0x7f];
for (i = 0; i < last_label; ++i) {
if (!strcmp(label, kLabels[i].label)) break;
}
if (i == MAX_NUM_LABELS) abort(); // overflow!
kLabels[i].label = label;
kLabels[i].size += pos - last_pos;
kLabels[i].count += 1;
if (i == last_label) ++last_label;
last_pos = pos;
}
#endif // BITTRACE > 0
//------------------------------------------------------------------------------

33
src/utils/bit_reader_utils.h
View File

@ -21,6 +21,27 @@
#endif
#include "src/webp/types.h"
// Warning! This macro triggers quite some MACRO wizardry around func signature!
#if !defined(BITTRACE)
#define BITTRACE 0 // 0 = off, 1 = print bits, 2 = print bytes
#endif
#if (BITTRACE > 0)
struct VP8BitReader;
extern void BitTrace(const struct VP8BitReader* const br, const char label[]);
#define BT_TRACK(br) BitTrace(br, label)
#define VP8Get(BR, L) VP8GetValue(BR, 1, L)
#else
#define BT_TRACK(br)
// We'll REMOVE the 'const char label[]' from all signatures and calls (!!):
#define VP8GetValue(BR, N, L) VP8GetValue(BR, N)
#define VP8Get(BR, L) VP8GetValue(BR, 1, L)
#define VP8GetSignedValue(BR, N, L) VP8GetSignedValue(BR, N)
#define VP8GetBit(BR, P, L) VP8GetBit(BR, P)
#define VP8GetBitAlt(BR, P, L) VP8GetBitAlt(BR, P)
#define VP8GetSigned(BR, V, L) VP8GetSigned(BR, V)
#endif
#ifdef __cplusplus
extern "C" {
#endif
@ -92,17 +113,15 @@ void VP8BitReaderSetBuffer(VP8BitReader* const br,
void VP8RemapBitReader(VP8BitReader* const br, ptrdiff_t offset);
// return the next value made of 'num_bits' bits
uint32_t VP8GetValue(VP8BitReader* const br, int num_bits);
static WEBP_INLINE uint32_t VP8Get(VP8BitReader* const br) {
return VP8GetValue(br, 1);
}
uint32_t VP8GetValue(VP8BitReader* const br, int num_bits, const char label[]);
// return the next value with sign-extension.
int32_t VP8GetSignedValue(VP8BitReader* const br, int num_bits);
int32_t VP8GetSignedValue(VP8BitReader* const br, int num_bits,
const char label[]);
// bit_reader_inl.h will implement the following methods:
// static WEBP_INLINE int VP8GetBit(VP8BitReader* const br, int prob)
// static WEBP_INLINE int VP8GetSigned(VP8BitReader* const br, int v)
// static WEBP_INLINE int VP8GetBit(VP8BitReader* const br, int prob, ...)
// static WEBP_INLINE int VP8GetSigned(VP8BitReader* const br, int v, ...)
// and should be included by the .c files that actually need them.
// This is to avoid recompiling the whole library whenever this file is touched,
// and also allowing platform-specific ad-hoc hacks.