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 
45 // size-checking safe malloc/calloc: verify that the requested size is not too
46 // large, or return NULL. You don't need to call these for constructs like
47 // malloc(sizeof(foo)), but only if there's picture-dependent size involved
48 // somewhere (like: malloc(num_pixels * sizeof(*something))). That's why this
49 // safe malloc() borrows the signature from calloc(), pointing at the dangerous
50 // underlying multiply involved.
51 WEBP_EXTERN void* WebPSafeMalloc(uint64_t nmemb, size_t size);
52 // Note that WebPSafeCalloc() expects the second argument type to be 'size_t'
53 // in order to favor the "calloc(num_foo, sizeof(foo))" pattern.
54 WEBP_EXTERN void* WebPSafeCalloc(uint64_t nmemb, size_t size);
55 
56 // Companion deallocation function to the above allocations.
57 WEBP_EXTERN void WebPSafeFree(void* const ptr);
58 
59 //------------------------------------------------------------------------------
60 // Alignment
61 
62 #define WEBP_ALIGN_CST 31
63 #define WEBP_ALIGN(PTR) (((uintptr_t)(PTR) + WEBP_ALIGN_CST) & ~WEBP_ALIGN_CST)
64 
65 #include <string.h>
66 // memcpy() is the safe way of moving potentially unaligned 32b memory.
67 static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) {
68   uint32_t A;
69   memcpy(&A, ptr, sizeof(A));
70   return A;
71 }
72 static WEBP_INLINE void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
73   memcpy(ptr, &val, sizeof(val));
74 }
75 
76 //------------------------------------------------------------------------------
77 // Reading/writing data.
78 
79 // Read 16, 24 or 32 bits stored in little-endian order.
80 static WEBP_INLINE int GetLE16(const uint8_t* const data) {
81   return (int)(data[0] << 0) | (data[1] << 8);
82 }
83 
84 static WEBP_INLINE int GetLE24(const uint8_t* const data) {
85   return GetLE16(data) | (data[2] << 16);
86 }
87 
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.
93 static WEBP_INLINE void PutLE16(uint8_t* const data, int val) {
94   assert(val < (1 << 16));
95   data[0] = (val >> 0) & 0xff;
96   data[1] = (val >> 8) & 0xff;
97 }
98 
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) & 0xff;
103 }
104 
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)
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 
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   // default: use the C-version.
128 // Returns 31 ^ clz(n) = log2(n). This is the default C-implementation, either
129 // based on table or not. Can be used as fallback if clz() is not available.
130 #define WEBP_NEED_LOG_TABLE_8BIT
131 extern const uint8_t WebPLogTable8bit[256];
132 static WEBP_INLINE int WebPLog2FloorC(uint32_t n) {
133   int log_value = 0;
134   while (n >= 256) {
135     log_value += 8;
136     n >>= 8;
137   }
138   return log_value + WebPLogTable8bit[n];
139 }
140 
141 static WEBP_INLINE int BitsLog2Floor(uint32_t n) { return WebPLog2FloorC(n); }
142 #endif
143 
144 //------------------------------------------------------------------------------
145 // Pixel copying.
146 
147 struct WebPPicture;
148 
149 // Copy width x height pixels from 'src' to 'dst' honoring the strides.
150 WEBP_EXTERN void WebPCopyPlane(const uint8_t* src, int src_stride,
151                                uint8_t* dst, int dst_stride,
152                                int width, int height);
153 
154 // Copy ARGB pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are
155 // assumed to be already allocated and using ARGB data.
156 WEBP_EXTERN void WebPCopyPixels(const struct WebPPicture* const src,
157                                 struct WebPPicture* const dst);
158 
159 //------------------------------------------------------------------------------
160 // Unique colors.
161 
162 // Returns count of unique colors in 'pic', assuming pic->use_argb is true.
163 // If the unique color count is more than MAX_PALETTE_SIZE, returns
164 // MAX_PALETTE_SIZE+1.
165 // If 'palette' is not NULL and number of unique colors is less than or equal to
166 // MAX_PALETTE_SIZE, also outputs the actual unique colors into 'palette'.
167 // Note: 'palette' is assumed to be an array already allocated with at least
168 // MAX_PALETTE_SIZE elements.
169 WEBP_EXTERN int WebPGetColorPalette(const struct WebPPicture* const pic,
170                                     uint32_t* const palette);
171 
172 //------------------------------------------------------------------------------
173 
174 #ifdef __cplusplus
175 }    // extern "C"
176 #endif
177 
178 #endif  // WEBP_UTILS_UTILS_H_
179