1
// Copyright 2012 Google Inc. All Rights Reserved.
3
// Use of this source code is governed by a BSD-style license
4
// that can be found in the COPYING file in the root of the source
5
// tree. An additional intellectual property rights grant can be found
6
// in the file PATENTS. All contributing project authors may
7
// be found in the AUTHORS file in the root of the source tree.
8
// -----------------------------------------------------------------------------
10
// Misc. common utility functions
12
// Authors: Skal (pascal.massimino@gmail.com)
13
// Urvang (urvang@google.com)
15
#ifndef WEBP_UTILS_UTILS_H_
16
#define WEBP_UTILS_UTILS_H_
20
#include "../webp/types.h"
26
//------------------------------------------------------------------------------
29
// This is the maximum memory amount that libwebp will ever try to allocate.
30
#define WEBP_MAX_ALLOCABLE_MEMORY (1ULL << 40)
32
// size-checking safe malloc/calloc: verify that the requested size is not too
33
// large, or return NULL. You don't need to call these for constructs like
34
// malloc(sizeof(foo)), but only if there's picture-dependent size involved
35
// somewhere (like: malloc(num_pixels * sizeof(*something))). That's why this
36
// safe malloc() borrows the signature from calloc(), pointing at the dangerous
37
// underlying multiply involved.
38
WEBP_EXTERN(void*) WebPSafeMalloc(uint64_t nmemb, size_t size);
39
// Note that WebPSafeCalloc() expects the second argument type to be 'size_t'
40
// in order to favor the "calloc(num_foo, sizeof(foo))" pattern.
41
WEBP_EXTERN(void*) WebPSafeCalloc(uint64_t nmemb, size_t size);
43
// Companion deallocation function to the above allocations.
44
WEBP_EXTERN(void) WebPSafeFree(void* const ptr);
46
//------------------------------------------------------------------------------
47
// Reading/writing data.
49
// Read 16, 24 or 32 bits stored in little-endian order.
50
static WEBP_INLINE int GetLE16(const uint8_t* const data) {
51
return (int)(data[0] << 0) | (data[1] << 8);
54
static WEBP_INLINE int GetLE24(const uint8_t* const data) {
55
return GetLE16(data) | (data[2] << 16);
58
static WEBP_INLINE uint32_t GetLE32(const uint8_t* const data) {
59
return (uint32_t)GetLE16(data) | (GetLE16(data + 2) << 16);
62
// Store 16, 24 or 32 bits in little-endian order.
63
static WEBP_INLINE void PutLE16(uint8_t* const data, int val) {
64
assert(val < (1 << 16));
69
static WEBP_INLINE void PutLE24(uint8_t* const data, int val) {
70
assert(val < (1 << 24));
71
PutLE16(data, val & 0xffff);
72
data[2] = (val >> 16);
75
static WEBP_INLINE void PutLE32(uint8_t* const data, uint32_t val) {
76
PutLE16(data, (int)(val & 0xffff));
77
PutLE16(data + 2, (int)(val >> 16));
80
// Returns (int)floor(log2(n)). n must be > 0.
81
// use GNU builtins where available.
82
#if defined(__GNUC__) && \
83
((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
84
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
85
return 31 ^ __builtin_clz(n);
87
#elif defined(_MSC_VER) && _MSC_VER > 1310 && \
88
(defined(_M_X64) || defined(_M_IX86))
90
#pragma intrinsic(_BitScanReverse)
92
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
93
uint32_t first_set_bit;
94
_BitScanReverse(&first_set_bit, n);
98
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
103
for (i = 4; i >= 0; --i) {
104
const int shift = (1 << i);
105
const uint32_t x = value >> shift;
115
//------------------------------------------------------------------------------
121
#endif /* WEBP_UTILS_UTILS_H_ */