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@gmail.com)
13// Urvang (urvang@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
29extern "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.
51WEBP_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.
54WEBP_EXTERN void* WebPSafeCalloc(uint64_t nmemb, size_t size);
55
56// Companion deallocation function to the above allocations.
57WEBP_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.
67static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) {
68 uint32_t A;
69 memcpy(&A, ptr, sizeof(A));
70 return A;
71}
72static 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.
80static WEBP_INLINE int GetLE16(const uint8_t* const data) {
81 return (int)(data[0] << 0) | (data[1] << 8);
82}
83
84static WEBP_INLINE int GetLE24(const uint8_t* const data) {
85 return GetLE16(data) | (data[2] << 16);
86}
87
88static 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.
93static WEBP_INLINE void PutLE16(uint8_t* const data, int val) {
94 assert(val < (1 << 16));
95 data[0] = (val >> 0) & 0xff;
96 data[1] = (val >> 8) & 0xff;
97}
98
99static 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) & 0xff;
103}
104
105static 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 (int)floor(log2(n)). n must be > 0.
111// use GNU builtins where available.
112#if defined(__GNUC__) && \
113 ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
114static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
115 return 31 ^ __builtin_clz(n);
116}
117#elif defined(_MSC_VER) && _MSC_VER > 1310 && \
118 (defined(_M_X64) || defined(_M_IX86))
119#include <intrin.h>
120#pragma intrinsic(_BitScanReverse)
121
122static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
123 unsigned long first_set_bit;
124 _BitScanReverse(&first_set_bit, n);
125 return first_set_bit;
126}
127#else // default: use the C-version.
128// Returns 31 ^ clz(n) = log2(n). This is the default C-implementation, either
129// based on table or not. Can be used as fallback if clz() is not available.
130#define WEBP_NEED_LOG_TABLE_8BIT
131extern const uint8_t WebPLogTable8bit[256];
132static WEBP_INLINE int WebPLog2FloorC(uint32_t n) {
133 int log_value = 0;
134 while (n >= 256) {
135 log_value += 8;
136 n >>= 8;
137 }
138 return log_value + WebPLogTable8bit[n];
139}
140
141static WEBP_INLINE int BitsLog2Floor(uint32_t n) { return WebPLog2FloorC(n); }
142#endif
143
144//------------------------------------------------------------------------------
145// Pixel copying.
146
147struct WebPPicture;
148
149// Copy width x height pixels from 'src' to 'dst' honoring the strides.
150WEBP_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.
156WEBP_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.
169WEBP_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