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 
15 class SkPackBits {
16 public:
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