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 "src/webp/config.h"
20 #endif
21
22 #include <assert.h>
23 #include <limits.h>
24
25 #include "src/dsp/dsp.h"
26 #include "src/webp/types.h"
27
28 #ifdef __cplusplus
29 extern "C" {
30 #endif
31
32 //------------------------------------------------------------------------------
33 // Memory allocation
34
35 // This is the maximum memory amount that libwebp will ever try to allocate.
36 #ifndef WEBP_MAX_ALLOCABLE_MEMORY
37 #if SIZE_MAX > (1ULL << 34)
38 #define WEBP_MAX_ALLOCABLE_MEMORY (1ULL << 34)
39 #else
40 // For 32-bit targets keep this below INT_MAX to avoid valgrind warnings.
41 #define WEBP_MAX_ALLOCABLE_MEMORY ((1ULL << 31) - (1 << 16))
42 #endif
43 #endif // WEBP_MAX_ALLOCABLE_MEMORY
44
CheckSizeOverflow(uint64_t size)45 static WEBP_INLINE int CheckSizeOverflow(uint64_t size) {
46 return size == (size_t)size;
47 }
48
49 // size-checking safe malloc/calloc: verify that the requested size is not too
50 // large, or return NULL. You don't need to call these for constructs like
51 // malloc(sizeof(foo)), but only if there's picture-dependent size involved
52 // somewhere (like: malloc(num_pixels * sizeof(*something))). That's why this
53 // safe malloc() borrows the signature from calloc(), pointing at the dangerous
54 // underlying multiply involved.
55 WEBP_EXTERN void* WebPSafeMalloc(uint64_t nmemb, size_t size);
56 // Note that WebPSafeCalloc() expects the second argument type to be 'size_t'
57 // in order to favor the "calloc(num_foo, sizeof(foo))" pattern.
58 WEBP_EXTERN void* WebPSafeCalloc(uint64_t nmemb, size_t size);
59
60 // Companion deallocation function to the above allocations.
61 WEBP_EXTERN void WebPSafeFree(void* const ptr);
62
63 //------------------------------------------------------------------------------
64 // Alignment
65
66 #define WEBP_ALIGN_CST 31
67 #define WEBP_ALIGN(PTR) (((uintptr_t)(PTR) + WEBP_ALIGN_CST) & \
68 ~(uintptr_t)WEBP_ALIGN_CST)
69
70 #include <string.h>
71 // memcpy() is the safe way of moving potentially unaligned 32b memory.
WebPMemToUint32(const uint8_t * const ptr)72 static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) {
73 uint32_t A;
74 memcpy(&A, ptr, sizeof(A));
75 return A;
76 }
77
WebPMemToInt32(const uint8_t * const ptr)78 static WEBP_INLINE int32_t WebPMemToInt32(const uint8_t* const ptr) {
79 return (int32_t)WebPMemToUint32(ptr);
80 }
81
WebPUint32ToMem(uint8_t * const ptr,uint32_t val)82 static WEBP_INLINE void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
83 memcpy(ptr, &val, sizeof(val));
84 }
85
WebPInt32ToMem(uint8_t * const ptr,int val)86 static WEBP_INLINE void WebPInt32ToMem(uint8_t* const ptr, int val) {
87 WebPUint32ToMem(ptr, (uint32_t)val);
88 }
89
90 //------------------------------------------------------------------------------
91 // Reading/writing data.
92
93 // Read 16, 24 or 32 bits stored in little-endian order.
GetLE16(const uint8_t * const data)94 static WEBP_INLINE int GetLE16(const uint8_t* const data) {
95 return (int)(data[0] << 0) | (data[1] << 8);
96 }
97
GetLE24(const uint8_t * const data)98 static WEBP_INLINE int GetLE24(const uint8_t* const data) {
99 return GetLE16(data) | (data[2] << 16);
100 }
101
GetLE32(const uint8_t * const data)102 static WEBP_INLINE uint32_t GetLE32(const uint8_t* const data) {
103 return GetLE16(data) | ((uint32_t)GetLE16(data + 2) << 16);
104 }
105
106 // Store 16, 24 or 32 bits in little-endian order.
PutLE16(uint8_t * const data,int val)107 static WEBP_INLINE void PutLE16(uint8_t* const data, int val) {
108 assert(val < (1 << 16));
109 data[0] = (val >> 0) & 0xff;
110 data[1] = (val >> 8) & 0xff;
111 }
112
PutLE24(uint8_t * const data,int val)113 static WEBP_INLINE void PutLE24(uint8_t* const data, int val) {
114 assert(val < (1 << 24));
115 PutLE16(data, val & 0xffff);
116 data[2] = (val >> 16) & 0xff;
117 }
118
PutLE32(uint8_t * const data,uint32_t val)119 static WEBP_INLINE void PutLE32(uint8_t* const data, uint32_t val) {
120 PutLE16(data, (int)(val & 0xffff));
121 PutLE16(data + 2, (int)(val >> 16));
122 }
123
124 // use GNU builtins where available.
125 #if defined(__GNUC__) && \
126 ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
127 // Returns (int)floor(log2(n)). n must be > 0.
BitsLog2Floor(uint32_t n)128 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
129 return 31 ^ __builtin_clz(n);
130 }
131 // counts the number of trailing zero
BitsCtz(uint32_t n)132 static WEBP_INLINE int BitsCtz(uint32_t n) { return __builtin_ctz(n); }
133 #elif defined(_MSC_VER) && _MSC_VER > 1310 && \
134 (defined(_M_X64) || defined(_M_IX86))
135 #include <intrin.h>
136 #pragma intrinsic(_BitScanReverse)
137 #pragma intrinsic(_BitScanForward)
138
BitsLog2Floor(uint32_t n)139 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
140 unsigned long first_set_bit; // NOLINT (runtime/int)
141 _BitScanReverse(&first_set_bit, n);
142 return first_set_bit;
143 }
BitsCtz(uint32_t n)144 static WEBP_INLINE int BitsCtz(uint32_t n) {
145 unsigned long first_set_bit; // NOLINT (runtime/int)
146 _BitScanForward(&first_set_bit, n);
147 return first_set_bit;
148 }
149 #else // default: use the (slow) C-version.
150 #define WEBP_HAVE_SLOW_CLZ_CTZ // signal that the Clz/Ctz function are slow
151 // Returns 31 ^ clz(n) = log2(n). This is the default C-implementation, either
152 // based on table or not. Can be used as fallback if clz() is not available.
153 #define WEBP_NEED_LOG_TABLE_8BIT
154 extern const uint8_t WebPLogTable8bit[256];
WebPLog2FloorC(uint32_t n)155 static WEBP_INLINE int WebPLog2FloorC(uint32_t n) {
156 int log_value = 0;
157 while (n >= 256) {
158 log_value += 8;
159 n >>= 8;
160 }
161 return log_value + WebPLogTable8bit[n];
162 }
163
BitsLog2Floor(uint32_t n)164 static WEBP_INLINE int BitsLog2Floor(uint32_t n) { return WebPLog2FloorC(n); }
165
BitsCtz(uint32_t n)166 static WEBP_INLINE int BitsCtz(uint32_t n) {
167 int i;
168 for (i = 0; i < 32; ++i, n >>= 1) {
169 if (n & 1) return i;
170 }
171 return 32;
172 }
173
174 #endif
175
176 //------------------------------------------------------------------------------
177 // Pixel copying.
178
179 struct WebPPicture;
180
181 // Copy width x height pixels from 'src' to 'dst' honoring the strides.
182 WEBP_EXTERN void WebPCopyPlane(const uint8_t* src, int src_stride,
183 uint8_t* dst, int dst_stride,
184 int width, int height);
185
186 // Copy ARGB pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are
187 // assumed to be already allocated and using ARGB data.
188 WEBP_EXTERN void WebPCopyPixels(const struct WebPPicture* const src,
189 struct WebPPicture* const dst);
190
191 //------------------------------------------------------------------------------
192 // Unique colors.
193
194 // Returns count of unique colors in 'pic', assuming pic->use_argb is true.
195 // If the unique color count is more than MAX_PALETTE_SIZE, returns
196 // MAX_PALETTE_SIZE+1.
197 // If 'palette' is not NULL and number of unique colors is less than or equal to
198 // MAX_PALETTE_SIZE, also outputs the actual unique colors into 'palette'.
199 // Note: 'palette' is assumed to be an array already allocated with at least
200 // MAX_PALETTE_SIZE elements.
201 WEBP_EXTERN int WebPGetColorPalette(const struct WebPPicture* const pic,
202 uint32_t* const palette);
203
204 //------------------------------------------------------------------------------
205
206 #ifdef __cplusplus
207 } // extern "C"
208 #endif
209
210 #endif // WEBP_UTILS_UTILS_H_
211