1
2/*
3 * Copyright 2008 The Android Open Source Project
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10#ifndef SkPackBits_DEFINED
11#define SkPackBits_DEFINED
12
13#include "SkTypes.h"
14
15class SkPackBits {
16public:
17    /** Given the number of 16bit values that will be passed to Pack16,
18        returns the worst-case size needed for the dst[] buffer.
19    */
20    static size_t ComputeMaxSize16(int count);
21
22    /** Given the number of 8bit values that will be passed to Pack8,
23        returns the worst-case size needed for the dst[] buffer.
24    */
25    static size_t ComputeMaxSize8(int count);
26
27    /** Write the src array into a packed format. The packing process may end
28        up writing more bytes than it read, so dst[] must be large enough.
29        @param src      Input array of 16bit values
30        @param count    Number of entries in src[]
31        @param dst      Buffer (allocated by caller) to write the packed data
32                        into
33        @return the number of bytes written to dst[]
34    */
35    static size_t Pack16(const uint16_t src[], int count, uint8_t dst[]);
36
37    /** Write the src array into a packed format. The packing process may end
38        up writing more bytes than it read, so dst[] must be large enough.
39        @param src      Input array of 8bit values
40        @param count    Number of entries in src[]
41        @param dst      Buffer (allocated by caller) to write the packed data
42                        into
43        @return the number of bytes written to dst[]
44    */
45    static size_t Pack8(const uint8_t src[], int count, uint8_t dst[]);
46
47    /** Unpack the data in src[], and expand it into dst[]. The src[] data was
48        written by a previous call to Pack16.
49        @param src  Input data to unpack, previously created by Pack16.
50        @param srcSize  Number of bytes of src to unpack
51        @param dst  Buffer (allocated by caller) to expand the src[] into.
52        @return the number of dst elements (not bytes) written into dst.
53    */
54    static int Unpack16(const uint8_t src[], size_t srcSize, uint16_t dst[]);
55
56    /** Unpack the data in src[], and expand it into dst[]. The src[] data was
57        written by a previous call to Pack8.
58        @param src      Input data to unpack, previously created by Pack8.
59        @param srcSize  Number of bytes of src to unpack
60        @param dst      Buffer (allocated by caller) to expand the src[] into.
61        @return the number of bytes written into dst.
62    */
63    static int Unpack8(const uint8_t src[], size_t srcSize, uint8_t dst[]);
64
65    /** Unpack the data from src[], skip the first dstSkip bytes, then write
66        dstWrite bytes into dst[]. The src[] data was written by a previous
67        call to Pack8. Return the number of bytes actually writtten into dst[]
68        @param src      Input data to unpack, previously created by Pack8.
69        @param dst      Buffer (allocated by caller) to expand the src[] into.
70        @param dstSkip  Number of bytes of unpacked src to skip before writing
71                        into dst
72        @param dstWrite Number of bytes of unpacked src to write into dst (after
73                        skipping dstSkip bytes)
74    */
75    static void Unpack8(uint8_t dst[], size_t dstSkip, size_t dstWrite,
76                        const uint8_t src[]);
77};
78
79#endif
80