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      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 #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);
     96   data[1] = (val >> 8);
     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);
    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 31 ^ clz(n) = log2(n). This is the default C-implementation, either
    111 // based on table or not. Can be used as fallback if clz() is not available.
    112 #define WEBP_NEED_LOG_TABLE_8BIT
    113 extern const uint8_t WebPLogTable8bit[256];
    114 static WEBP_INLINE int WebPLog2FloorC(uint32_t n) {
    115   int log_value = 0;
    116   while (n >= 256) {
    117     log_value += 8;
    118     n >>= 8;
    119   }
    120   return log_value + WebPLogTable8bit[n];
    121 }
    122 
    123 // Returns (int)floor(log2(n)). n must be > 0.
    124 // use GNU builtins where available.
    125 #if defined(__GNUC__) && \
    126     ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
    127 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
    128   return 31 ^ __builtin_clz(n);
    129 }
    130 #elif defined(_MSC_VER) && _MSC_VER > 1310 && \
    131       (defined(_M_X64) || defined(_M_IX86))
    132 #include <intrin.h>
    133 #pragma intrinsic(_BitScanReverse)
    134 
    135 static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
    136   unsigned long first_set_bit;
    137   _BitScanReverse(&first_set_bit, n);
    138   return first_set_bit;
    139 }
    140 #else   // default: use the C-version.
    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