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- // 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_ */
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