| // Copyright 2012 Google Inc. All Rights Reserved. |
| // |
| // Use of this source code is governed by a BSD-style license |
| // that can be found in the COPYING file in the root of the source |
| // tree. An additional intellectual property rights grant can be found |
| // in the file PATENTS. All contributing project authors may |
| // be found in the AUTHORS file in the root of the source tree. |
| // ----------------------------------------------------------------------------- |
| // |
| // Misc. common utility functions |
| // |
| // Authors: Skal (pascal.massimino@gmail.com) |
| // Urvang (urvang@google.com) |
| |
| #ifndef WEBP_UTILS_UTILS_H_ |
| #define WEBP_UTILS_UTILS_H_ |
| |
| #include <assert.h> |
| |
| #include "webp/types.h" |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| //------------------------------------------------------------------------------ |
| // Memory allocation |
| |
| // This is the maximum memory amount that libwebp will ever try to allocate. |
| #define WEBP_MAX_ALLOCABLE_MEMORY (1ULL << 40) |
| |
| // size-checking safe malloc/calloc: verify that the requested size is not too |
| // large, or return NULL. You don't need to call these for constructs like |
| // malloc(sizeof(foo)), but only if there's picture-dependent size involved |
| // somewhere (like: malloc(num_pixels * sizeof(*something))). That's why this |
| // safe malloc() borrows the signature from calloc(), pointing at the dangerous |
| // underlying multiply involved. |
| WEBP_EXTERN(void*) WebPSafeMalloc(uint64_t nmemb, size_t size); |
| // Note that WebPSafeCalloc() expects the second argument type to be 'size_t' |
| // in order to favor the "calloc(num_foo, sizeof(foo))" pattern. |
| WEBP_EXTERN(void*) WebPSafeCalloc(uint64_t nmemb, size_t size); |
| |
| // Companion deallocation function to the above allocations. |
| WEBP_EXTERN(void) WebPSafeFree(void* const ptr); |
| |
| //------------------------------------------------------------------------------ |
| // Reading/writing data. |
| |
| // Read 16, 24 or 32 bits stored in little-endian order. |
| static WEBP_INLINE int GetLE16(const uint8_t* const data) { |
| return (int)(data[0] << 0) | (data[1] << 8); |
| } |
| |
| static WEBP_INLINE int GetLE24(const uint8_t* const data) { |
| return GetLE16(data) | (data[2] << 16); |
| } |
| |
| static WEBP_INLINE uint32_t GetLE32(const uint8_t* const data) { |
| return (uint32_t)GetLE16(data) | (GetLE16(data + 2) << 16); |
| } |
| |
| // Store 16, 24 or 32 bits in little-endian order. |
| static WEBP_INLINE void PutLE16(uint8_t* const data, int val) { |
| assert(val < (1 << 16)); |
| data[0] = (val >> 0); |
| data[1] = (val >> 8); |
| } |
| |
| static WEBP_INLINE void PutLE24(uint8_t* const data, int val) { |
| assert(val < (1 << 24)); |
| PutLE16(data, val & 0xffff); |
| data[2] = (val >> 16); |
| } |
| |
| static WEBP_INLINE void PutLE32(uint8_t* const data, uint32_t val) { |
| PutLE16(data, (int)(val & 0xffff)); |
| PutLE16(data + 2, (int)(val >> 16)); |
| } |
| |
| // Returns (int)floor(log2(n)). n must be > 0. |
| // use GNU builtins where available. |
| #if defined(__GNUC__) && \ |
| ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4) |
| static WEBP_INLINE int BitsLog2Floor(uint32_t n) { |
| return 31 ^ __builtin_clz(n); |
| } |
| #elif defined(_MSC_VER) && _MSC_VER > 1310 && \ |
| (defined(_M_X64) || defined(_M_IX86)) |
| #include <intrin.h> |
| #pragma intrinsic(_BitScanReverse) |
| |
| static WEBP_INLINE int BitsLog2Floor(uint32_t n) { |
| uint32_t first_set_bit; |
| _BitScanReverse(&first_set_bit, n); |
| return first_set_bit; |
| } |
| #else |
| static WEBP_INLINE int BitsLog2Floor(uint32_t n) { |
| int log = 0; |
| uint32_t value = n; |
| int i; |
| |
| for (i = 4; i >= 0; --i) { |
| const int shift = (1 << i); |
| const uint32_t x = value >> shift; |
| if (x != 0) { |
| value = x; |
| log += shift; |
| } |
| } |
| return log; |
| } |
| #endif |
| |
| //------------------------------------------------------------------------------ |
| |
| #ifdef __cplusplus |
| } // extern "C" |
| #endif |
| |
| #endif /* WEBP_UTILS_UTILS_H_ */ |