1 | /* -*- tab-width: 4; -*- */ |
2 | /* vi: set sw=2 ts=4 expandtab: */ |
3 | |
4 | /* Copyright 2019-2020 The Khronos Group Inc. |
5 | * SPDX-License-Identifier: Apache-2.0 |
6 | */ |
7 | |
8 | /** |
9 | * @file |
10 | * @~English |
11 | * @brief Utilities for querying info from a data format descriptor. |
12 | * @author Mark Callow |
13 | */ |
14 | |
15 | #include <stdint.h> |
16 | #include <stdio.h> |
17 | #include <stdlib.h> |
18 | #include <string.h> |
19 | #include <KHR/khr_df.h> |
20 | #include "dfd.h" |
21 | |
22 | /** |
23 | * @~English |
24 | * @brief Get the number and size of the image components from a DFD. |
25 | * |
26 | * This simplified function is for use only with the DFDs for unpacked |
27 | * formats which means all components have the same size. |
28 | * |
29 | * @param DFD Pointer to a Data Format Descriptor to interpret, |
30 | described as 32-bit words in native endianness. |
31 | Note that this is the whole descriptor, not just |
32 | the basic descriptor block. |
33 | * @param numComponents pointer to a 32-bit word in which the number of |
34 | components will be written. |
35 | * @param componentByteLength pointer to a 32-bit word in which the size of |
36 | a component in bytes will be written. |
37 | */ |
38 | void |
39 | getDFDComponentInfoUnpacked(const uint32_t* DFD, uint32_t* numComponents, |
40 | uint32_t* componentByteLength) |
41 | { |
42 | const uint32_t *BDFDB = DFD+1; |
43 | uint32_t numSamples = KHR_DFDSAMPLECOUNT(BDFDB); |
44 | uint32_t sampleCounter; |
45 | uint32_t currentChannel = ~0U; /* Don't start matched. */ |
46 | |
47 | /* This is specifically for unpacked formats which means the size of */ |
48 | /* each component is the same. */ |
49 | *numComponents = 0; |
50 | for (sampleCounter = 0; sampleCounter < numSamples; ++sampleCounter) { |
51 | uint32_t sampleByteLength = (KHR_DFDSVAL(BDFDB, sampleCounter, BITLENGTH) + 1) >> 3U; |
52 | uint32_t sampleChannel = KHR_DFDSVAL(BDFDB, sampleCounter, CHANNELID); |
53 | |
54 | if (sampleChannel == currentChannel) { |
55 | /* Continuation of the same channel. */ |
56 | /* Accumulate the byte length. */ |
57 | *componentByteLength += sampleByteLength; |
58 | } else { |
59 | /* Everything is new. Hopefully. */ |
60 | currentChannel = sampleChannel; |
61 | (*numComponents)++; |
62 | *componentByteLength = sampleByteLength; |
63 | } |
64 | } |
65 | } |
66 | |
67 | /** |
68 | * @~English |
69 | * @brief Return the number of "components" in the data. |
70 | * |
71 | * Calculates the number of uniques samples in the DFD by combining |
72 | * multiple samples for the same channel. For uncompressed colorModels |
73 | * this is the same as the number of components in the image data. For |
74 | * block-compressed color models this is the number of samples in |
75 | * the color model, typically 1 and in a few cases 2. |
76 | * |
77 | * @param DFD Pointer to a Data Format Descriptor for which, |
78 | * described as 32-bit words in native endianness. |
79 | * Note that this is the whole descriptor, not just |
80 | * the basic descriptor block. |
81 | */ |
82 | uint32_t getDFDNumComponents(const uint32_t* DFD) |
83 | { |
84 | const uint32_t *BDFDB = DFD+1; |
85 | uint32_t currentChannel = ~0U; /* Don't start matched. */ |
86 | uint32_t numComponents = 0; |
87 | uint32_t numSamples = KHR_DFDSAMPLECOUNT(BDFDB); |
88 | uint32_t sampleCounter; |
89 | |
90 | for (sampleCounter = 0; sampleCounter < numSamples; ++sampleCounter) { |
91 | uint32_t sampleChannel = KHR_DFDSVAL(BDFDB, sampleCounter, CHANNELID); |
92 | if (sampleChannel != currentChannel) { |
93 | numComponents++; |
94 | currentChannel = sampleChannel; |
95 | } |
96 | } |
97 | return numComponents; |
98 | } |
99 | |
100 | /** |
101 | * @~English |
102 | * @brief Recreate the value of bytesPlane0 from sample info. |
103 | * |
104 | * This can be use to recreate the value of bytesPlane0 for data that |
105 | * has been variable-rate compressed so has bytesPlane0 = 0. For DFDs |
106 | * that are valid for KTX files. Little-endian data only and no multi-plane |
107 | * formats. |
108 | * |
109 | * @param DFD Pointer to a Data Format Descriptor for which, |
110 | * described as 32-bit words in native endianness. |
111 | * Note that this is the whole descriptor, not just |
112 | * the basic descriptor block. |
113 | * @param bytesPlane0 pointer to a 32-bit word in which the recreated |
114 | * value of bytesPlane0 will be written. |
115 | */ |
116 | void |
117 | recreateBytesPlane0FromSampleInfo(const uint32_t* DFD, uint32_t* bytesPlane0) |
118 | { |
119 | const uint32_t *BDFDB = DFD+1; |
120 | uint32_t numSamples = KHR_DFDSAMPLECOUNT(BDFDB); |
121 | uint32_t sampleCounter; |
122 | |
123 | uint32_t bitsPlane0 = 0; |
124 | uint32_t* bitOffsets = malloc(sizeof(uint32_t) * numSamples); |
125 | memset(bitOffsets, -1, sizeof(uint32_t) * numSamples); |
126 | for (sampleCounter = 0; sampleCounter < numSamples; ++sampleCounter) { |
127 | uint32_t sampleBitOffset = KHR_DFDSVAL(BDFDB, sampleCounter, BITOFFSET); |
128 | /* The sample bitLength field stores the bit length - 1. */ |
129 | uint32_t sampleBitLength = KHR_DFDSVAL(BDFDB, sampleCounter, BITLENGTH) + 1; |
130 | uint32_t i; |
131 | for (i = 0; i < numSamples; i++) { |
132 | if (sampleBitOffset == bitOffsets[i]) { |
133 | // This sample is being repeated as in e.g. RGB9E5. |
134 | break; |
135 | } |
136 | } |
137 | if (i == numSamples) { |
138 | // Previously unseen bitOffset. Bump size. |
139 | bitsPlane0 += sampleBitLength; |
140 | bitOffsets[sampleCounter] = sampleBitOffset; |
141 | } |
142 | } |
143 | free(bitOffsets); |
144 | *bytesPlane0 = bitsPlane0 >> 3U; |
145 | } |
146 | |
147 | |