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 (at) gmail.com) 13 // Urvang (urvang (at) google.com) 14 15 #ifndef WEBP_UTILS_UTILS_H_ 16 #define WEBP_UTILS_UTILS_H_ 17 18 #include <assert.h> 19 20 #include "../webp/types.h" 21 22 #ifdef __cplusplus 23 extern "C" { 24 #endif 25 26 //------------------------------------------------------------------------------ 27 // Memory allocation 28 29 // This is the maximum memory amount that libwebp will ever try to allocate. 30 #define WEBP_MAX_ALLOCABLE_MEMORY (1ULL << 40) 31 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); 42 43 // Companion deallocation function to the above allocations. 44 WEBP_EXTERN(void) WebPSafeFree(void* const ptr); 45 46 //------------------------------------------------------------------------------ 47 // Reading/writing data. 48 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); 52 } 53 54 static WEBP_INLINE int GetLE24(const uint8_t* const data) { 55 return GetLE16(data) | (data[2] << 16); 56 } 57 58 static WEBP_INLINE uint32_t GetLE32(const uint8_t* const data) { 59 return (uint32_t)GetLE16(data) | (GetLE16(data + 2) << 16); 60 } 61 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)); 65 data[0] = (val >> 0); 66 data[1] = (val >> 8); 67 } 68 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); 73 } 74 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)); 78 } 79 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); 86 } 87 #elif defined(_MSC_VER) && _MSC_VER > 1310 && \ 88 (defined(_M_X64) || defined(_M_IX86)) 89 #include <intrin.h> 90 #pragma intrinsic(_BitScanReverse) 91 92 static WEBP_INLINE int BitsLog2Floor(uint32_t n) { 93 uint32_t first_set_bit; 94 _BitScanReverse(&first_set_bit, n); 95 return first_set_bit; 96 } 97 #else 98 static WEBP_INLINE int BitsLog2Floor(uint32_t n) { 99 int log = 0; 100 uint32_t value = n; 101 int i; 102 103 for (i = 4; i >= 0; --i) { 104 const int shift = (1 << i); 105 const uint32_t x = value >> shift; 106 if (x != 0) { 107 value = x; 108 log += shift; 109 } 110 } 111 return log; 112 } 113 #endif 114 115 //------------------------------------------------------------------------------ 116 117 #ifdef __cplusplus 118 } // extern "C" 119 #endif 120 121 #endif /* WEBP_UTILS_UTILS_H_ */ 122
