libwebp-0.6.0-rc1

third_party/libwebp/utils/utils.h

 // 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
@@ skipping 44 matching lines @@
 
 // Companion deallocation function to the above allocations.
 WEBP_EXTERN(void) WebPSafeFree(void* const ptr);
 
 //------------------------------------------------------------------------------
 // Alignment
 
 #define WEBP_ALIGN_CST 31
 #define WEBP_ALIGN(PTR) (((uintptr_t)(PTR) + WEBP_ALIGN_CST) & ~WEBP_ALIGN_CST)
 
-#if defined(WEBP_FORCE_ALIGNED)
 #include <string.h>
 // memcpy() is the safe way of moving potentially unaligned 32b memory.
 static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) {
   uint32_t A;
   memcpy(&A, (const int*)ptr, sizeof(A));
   return A;
 }
 static WEBP_INLINE void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
   memcpy(ptr, &val, sizeof(val));
 }
-#else
-static WEBP_UBSAN_IGNORE_UNDEF WEBP_INLINE
-uint32_t WebPMemToUint32(const uint8_t* const ptr) {
-  return *(const uint32_t*)ptr;
-}
-static WEBP_UBSAN_IGNORE_UNDEF WEBP_INLINE
-void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) {
-  *(uint32_t*)ptr = val;
-}
-#endif
 
 //------------------------------------------------------------------------------
 // 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) {
@@ skipping 15 matching lines @@
   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 31 ^ clz(n) = log2(n). This is the default C-implementation, either
+// based on table or not. Can be used as fallback if clz() is not available.
+#define WEBP_NEED_LOG_TABLE_8BIT
+extern const uint8_t WebPLogTable8bit[256];
+static WEBP_INLINE int WebPLog2FloorC(uint32_t n) {
+  int log = 0;
+  while (n >= 256) {
+    log += 8;
+    n >>= 8;
+  }
+  return log + WebPLogTable8bit[n];
+}
+
 // 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) {
   unsigned long 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;
-}
+#else   // default: use the C-version.
+static WEBP_INLINE int BitsLog2Floor(uint32_t n) { return WebPLog2FloorC(n); }
 #endif
 
 //------------------------------------------------------------------------------
 // Pixel copying.
 
 struct WebPPicture;
 
 // Copy width x height pixels from 'src' to 'dst' honoring the strides.
 WEBP_EXTERN(void) WebPCopyPlane(const uint8_t* src, int src_stride,
                                 uint8_t* dst, int dst_stride,
                                 int width, int height);
 
 // Copy ARGB pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are
 // assumed to be already allocated and using ARGB data.
 WEBP_EXTERN(void) WebPCopyPixels(const struct WebPPicture* const src,
                                  struct WebPPicture* const dst);
 
 //------------------------------------------------------------------------------
 // Unique colors.
 
 // Returns count of unique colors in 'pic', assuming pic->use_argb is true.
-// If the unique color count is more than MAX_COLOR_COUNT, returns
-// MAX_COLOR_COUNT+1.
+// If the unique color count is more than MAX_PALETTE_SIZE, returns
+// MAX_PALETTE_SIZE+1.
 // If 'palette' is not NULL and number of unique colors is less than or equal to
-// MAX_COLOR_COUNT, also outputs the actual unique colors into 'palette'.
+// MAX_PALETTE_SIZE, also outputs the actual unique colors into 'palette'.
 // Note: 'palette' is assumed to be an array already allocated with at least
-// MAX_COLOR_COUNT elements.
+// MAX_PALETTE_SIZE elements.
 WEBP_EXTERN(int) WebPGetColorPalette(const struct WebPPicture* const pic,
                                      uint32_t* const palette);
 
 //------------------------------------------------------------------------------
 
 #ifdef __cplusplus
 }    // extern "C"
 #endif
 
 #endif  /* WEBP_UTILS_UTILS_H_ */