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