1 // Copyright 2012 Google Inc. All Rights Reserved.
2 //
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 // -----------------------------------------------------------------------------
9 //
10 // Misc. common utility functions
11 //
12 // Authors: Skal (pascal.massimino@gmail.com)
13 // Urvang (urvang@google.com)
14
15 #ifndef WEBP_UTILS_UTILS_H_
16 #define WEBP_UTILS_UTILS_H_
17
18 #ifdef HAVE_CONFIG_H
19 #include "../webp/config.h"
20 #endif
21
22 #include <assert.h>
23
24 #include "../webp/types.h"
25
26 #ifdef __cplusplus
27 extern "C" {
28 #endif
29
30 //------------------------------------------------------------------------------
31 // Memory allocation
32
33 // This is the maximum memory amount that libwebp will ever try to allocate.
34 #define WEBP_MAX_ALLOCABLE_MEMORY (1ULL << 40)
35
36 // size-checking safe malloc/calloc: verify that the requested size is not too
37 // large, or return NULL. You don't need to call these for constructs like
38 // malloc(sizeof(foo)), but only if there's picture-dependent size involved
39 // somewhere (like: malloc(num_pixels * sizeof(*something))). That's why this
40 // safe malloc() borrows the signature from calloc(), pointing at the dangerous
41 // underlying multiply involved.
42 WEBP_EXTERN(void*) WebPSafeMalloc(uint64_t nmemb, size_t size);
43 // Note that WebPSafeCalloc() expects the second argument type to be 'size_t'
44 // in order to favor the "calloc(num_foo, sizeof(foo))" pattern.
45 WEBP_EXTERN(void*) WebPSafeCalloc(uint64_t nmemb, size_t size);
46
47 // Companion deallocation function to the above allocations.
48 WEBP_EXTERN(void) WebPSafeFree(void* const ptr);
49
50 //------------------------------------------------------------------------------
51 // Alignment
52
53 #define WEBP_ALIGN_CST 31
54 #define WEBP_ALIGN(PTR) ((uintptr_t)((PTR) + WEBP_ALIGN_CST) & ~WEBP_ALIGN_CST)
55
56 #if defined(WEBP_FORCE_ALIGNED)
57 #include <string.h>
58 // memcpy() is the safe way of moving potentially unaligned 32b memory.
WebPMemToUint32(const uint8_t * const ptr)59 static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) {
60 uint32_t A;
61 memcpy(&A, (const int*)ptr, sizeof(A));
62 return A;
63 }
WebPUint32ToMem(uint8_t * const ptr,uint32_t val)64 static WEBP_INLINE void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
65 memcpy(ptr, &val, sizeof(val));
66 }
67 #else
WebPMemToUint32(const uint8_t * const ptr)68 static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) {
69 return *(const uint32_t*)ptr;
70 }
WebPUint32ToMem(uint8_t * const ptr,uint32_t val)71 static WEBP_INLINE void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
72 *(uint32_t*)ptr = val;
73 }
74 #endif
75
76 //------------------------------------------------------------------------------
77 // Reading/writing data.
78
79 // Read 16, 24 or 32 bits stored in little-endian order.
GetLE16(const uint8_t * const data)80 static WEBP_INLINE int GetLE16(const uint8_t* const data) {
81 return (int)(data[0] << 0) | (data[1] << 8);
82 }
83
GetLE24(const uint8_t * const data)84 static WEBP_INLINE int GetLE24(const uint8_t* const data) {
85 return GetLE16(data) | (data[2] << 16);
86 }
87
GetLE32(const uint8_t * const data)88 static WEBP_INLINE uint32_t GetLE32(const uint8_t* const data) {
89 return GetLE16(data) | ((uint32_t)GetLE16(data + 2) << 16);
90 }
91
92 // Store 16, 24 or 32 bits in little-endian order.
PutLE16(uint8_t * const data,int val)93 static WEBP_INLINE void PutLE16(uint8_t* const data, int val) {
94 assert(val < (1 << 16));
95 data[0] = (val >> 0);
96 data[1] = (val >> 8);
97 }
98
PutLE24(uint8_t * const data,int val)99 static WEBP_INLINE void PutLE24(uint8_t* const data, int val) {
100 assert(val < (1 << 24));
101 PutLE16(data, val & 0xffff);
102 data[2] = (val >> 16);
103 }
104
PutLE32(uint8_t * const data,uint32_t val)105 static WEBP_INLINE void PutLE32(uint8_t* const data, uint32_t val) {
106 PutLE16(data, (int)(val & 0xffff));
107 PutLE16(data + 2, (int)(val >> 16));
108 }
109
110 // Returns (int)floor(log2(n)). n must be > 0.
111 // use GNU builtins where available.
112 #if defined(__GNUC__) && \
113 ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
BitsLog2Floor(uint32_t n)114 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
115 return 31 ^ __builtin_clz(n);
116 }
117 #elif defined(_MSC_VER) && _MSC_VER > 1310 && \
118 (defined(_M_X64) || defined(_M_IX86))
119 #include <intrin.h>
120 #pragma intrinsic(_BitScanReverse)
121
BitsLog2Floor(uint32_t n)122 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
123 unsigned long first_set_bit;
124 _BitScanReverse(&first_set_bit, n);
125 return first_set_bit;
126 }
127 #else
BitsLog2Floor(uint32_t n)128 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
129 int log = 0;
130 uint32_t value = n;
131 int i;
132
133 for (i = 4; i >= 0; --i) {
134 const int shift = (1 << i);
135 const uint32_t x = value >> shift;
136 if (x != 0) {
137 value = x;
138 log += shift;
139 }
140 }
141 return log;
142 }
143 #endif
144
145 //------------------------------------------------------------------------------
146 // Pixel copying.
147
148 struct WebPPicture;
149
150 // Copy width x height pixels from 'src' to 'dst' honoring the strides.
151 WEBP_EXTERN(void) WebPCopyPlane(const uint8_t* src, int src_stride,
152 uint8_t* dst, int dst_stride,
153 int width, int height);
154
155 // Copy ARGB pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are
156 // assumed to be already allocated and using ARGB data.
157 WEBP_EXTERN(void) WebPCopyPixels(const struct WebPPicture* const src,
158 struct WebPPicture* const dst);
159
160 //------------------------------------------------------------------------------
161
162 #ifdef __cplusplus
163 } // extern "C"
164 #endif
165
166 #endif /* WEBP_UTILS_UTILS_H_ */
167