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Fixing tabs
This commit is contained in:
Rich Geldreich
@@ -213,41 +213,41 @@ First, some enums:
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enum
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{
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// Max supported Huffman code size is 16-bits
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cHuffmanMaxSupportedCodeSize = 16,
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// Max supported Huffman code size is 16-bits
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cHuffmanMaxSupportedCodeSize = 16,
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// The maximum number of symbols is 2^14
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cHuffmanMaxSymsLog2 = 14,
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cHuffmanMaxSyms = 1 << cHuffmanMaxSymsLog2,
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// The maximum number of symbols is 2^14
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cHuffmanMaxSymsLog2 = 14,
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cHuffmanMaxSyms = 1 << cHuffmanMaxSymsLog2,
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// Small zero runs may range from 3-10 entries
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cHuffmanSmallZeroRunSizeMin = 3,
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cHuffmanSmallZeroRunSizeMax = 10,
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cHuffmanSmallZeroRunExtraBits = 3,
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// Small zero runs may range from 3-10 entries
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cHuffmanSmallZeroRunSizeMin = 3,
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cHuffmanSmallZeroRunSizeMax = 10,
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cHuffmanSmallZeroRunExtraBits = 3,
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// Big zero runs may range from 11-138 entries
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cHuffmanBigZeroRunSizeMin = 11,
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cHuffmanBigZeroRunSizeMax = 138,
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cHuffmanBigZeroRunExtraBits = 7,
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// Big zero runs may range from 11-138 entries
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cHuffmanBigZeroRunSizeMin = 11,
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cHuffmanBigZeroRunSizeMax = 138,
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cHuffmanBigZeroRunExtraBits = 7,
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// Small non-zero runs may range from 3-6 entries
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cHuffmanSmallRepeatSizeMin = 3,
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cHuffmanSmallRepeatSizeMax = 6,
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cHuffmanSmallRepeatExtraBits = 2,
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// Small non-zero runs may range from 3-6 entries
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cHuffmanSmallRepeatSizeMin = 3,
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cHuffmanSmallRepeatSizeMax = 6,
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cHuffmanSmallRepeatExtraBits = 2,
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// Big non-zero run may range from 7-134 entries
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cHuffmanBigRepeatSizeMin = 7,
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cHuffmanBigRepeatSizeMax = 134,
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cHuffmanBigRepeatExtraBits = 7,
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// Big non-zero run may range from 7-134 entries
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cHuffmanBigRepeatSizeMin = 7,
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cHuffmanBigRepeatSizeMax = 134,
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cHuffmanBigRepeatExtraBits = 7,
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// There are a maximum of 21 symbols in a compressed Huffman code length table.
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cHuffmanTotalCodelengthCodes = 21,
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// Symbols [0,16] indicate code sizes. Other symbols indicate zero runs or repeats:
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cHuffmanSmallZeroRunCode = 17,
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cHuffmanBigZeroRunCode = 18,
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cHuffmanSmallRepeatCode = 19,
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cHuffmanBigRepeatCode = 20
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// There are a maximum of 21 symbols in a compressed Huffman code length table.
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cHuffmanTotalCodelengthCodes = 21,
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// Symbols [0,16] indicate code sizes. Other symbols indicate zero runs or repeats:
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cHuffmanSmallZeroRunCode = 17,
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cHuffmanBigZeroRunCode = 18,
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cHuffmanSmallRepeatCode = 19,
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cHuffmanBigRepeatCode = 20
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};
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A .basis Huffman table consists of 1 to cHuffmanMaxSyms symbols. Each compressed
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@@ -257,43 +257,43 @@ The table's symbol code lengths are themselves RLE+Huffman coded, just like
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Deflate. (Note this can be confusing to developers unfamiliar with Deflate.)
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Each table begins with a small fixed header:
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14 bits: total_used_syms [1, cHuffmanMaxSyms]
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5 bits: num_codelength_codes [1, cHuffmanTotalCodelengthCodes]
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Next, the code lengths for the small Huffman table which is used to send the compressed codelengths (and RLE/repeat codes) are sent uncompressed but in a reordered manner:
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3*num_codelength_codes bits: Code size of each Huffman symbol for the compressed Huffman codelength table.
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14 bits: total_used_syms [1, cHuffmanMaxSyms]
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5 bits: num_codelength_codes [1, cHuffmanTotalCodelengthCodes]
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These code lengths are sent in this order (to help reduce the number that must be sent):
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{
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cHuffmanSmallZeroRunCode, cHuffmanBigZeroRunCode, cHuffmanSmallRepeatCode, cHuffmanBigRepeatCode,
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0, 8, 7, 9, 6, 0xA, 5, 0xB, 4, 0xC, 3, 0xD, 2, 0xE, 1, 0xF, 0x10
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};
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Next, the code lengths for the small Huffman table which is used to send the compressed codelengths (and RLE/repeat codes) are sent uncompressed but in a reordered manner:
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3*num_codelength_codes bits: Code size of each Huffman symbol for the compressed Huffman codelength table.
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These code lengths are sent in this order (to help reduce the number that must be sent):
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{
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cHuffmanSmallZeroRunCode, cHuffmanBigZeroRunCode, cHuffmanSmallRepeatCode, cHuffmanBigRepeatCode,
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0, 8, 7, 9, 6, 0xA, 5, 0xB, 4, 0xC, 3, 0xD, 2, 0xE, 1, 0xF, 0x10
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};
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A canonical Huffman decoding table (of up to 21 symbols) should be built from
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these code lengths. Immediately following this data are the Huffman symbols
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(sometimes intermixed with raw bits) which describe how to unpack the
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codelengths of each symbol in the Huffman table:
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- Symbols [0,16] indicate a specific symbol code length in bits.
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- Symbol cHuffmanSmallZeroRunCode (17) indicates a short run of symbols with 0 bit code lengths.
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cHuffmanSmallZeroRunExtraBits (3) bits are sent after this symbol, which indicates the run's size after adding the minimum size (cHuffmanSmallZeroRunSizeMin).
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- Symbol cHuffmanBigZeroRunCode (18) indicates a long run of symbols with 0 bit code lengths.
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cHuffmanBigZeroRunExtraBits (7) bits are sent after this symbol, which indicates the run's size after adding the minimum size (cHuffmanBigZeroRunSizeMin)
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- Symbols [0,16] indicate a specific symbol code length in bits.
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- Symbol cHuffmanSmallZeroRunCode (17) indicates a short run of symbols with 0 bit code lengths.
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cHuffmanSmallZeroRunExtraBits (3) bits are sent after this symbol, which indicates the run's size after adding the minimum size (cHuffmanSmallZeroRunSizeMin).
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- Symbol cHuffmanBigZeroRunCode (18) indicates a long run of symbols with 0 bit code lengths.
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cHuffmanBigZeroRunExtraBits (7) bits are sent after this symbol, which indicates the run's size after adding the minimum size (cHuffmanBigZeroRunSizeMin)
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- Symbol cHuffmanSmallRepeatCode (19) indicates a short run of symbols that repeat the previous symbol's code length.
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cHuffmanSmallRepeatExtraBits (2) bits are sent after this symbol, which indicates the number of times to repeat the previous symbol's code length,
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after adding the minimum size (cHuffmanSmallRepeatSizeMin).
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Cannot be the first symbol, and the previous symbol cannot have a code length of 0.
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- Symbol cHuffmanBigRepeatCode (20) indicates a short run of symbols that repeat the previous symbol's code length.
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cHuffmanBigRepeatExtraBits (7) bits are sent after this symbol, which indicates the number of times to repeat the previous symbol's code length,
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after adding the minimum size (cHuffmanBigRepeatSizeMin).
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Cannot be the first symbol, and the previous symbol cannot have a code length of 0.
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- Symbol cHuffmanSmallRepeatCode (19) indicates a short run of symbols that repeat the previous symbol's code length.
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cHuffmanSmallRepeatExtraBits (2) bits are sent after this symbol, which indicates the number of times to repeat the previous symbol's code length,
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after adding the minimum size (cHuffmanSmallRepeatSizeMin).
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Cannot be the first symbol, and the previous symbol cannot have a code length of 0.
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- Symbol cHuffmanBigRepeatCode (20) indicates a short run of symbols that repeat the previous symbol's code length.
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cHuffmanBigRepeatExtraBits (7) bits are sent after this symbol, which indicates the number of times to repeat the previous symbol's code length,
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after adding the minimum size (cHuffmanBigRepeatSizeMin).
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Cannot be the first symbol, and the previous symbol cannot have a code length of 0.
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There should be exactly total_used_syms code lengths stored in the compressed Huffman table. If not the stream is either corrupted or invalid.
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After all the symbol codelengths are uncompressed, the symbol codes can be computed and the canonical Huffman decoding tables can be built.
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@@ -310,10 +310,10 @@ At the beginning of the compressed endpoint codebook section are four compressed
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Huffman tables, stored using the procedure outlined in section 6.0. The Huffman tables
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appear in this order:
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1. color5_delta_model0
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2. color5_delta_model1
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3. color5_delta_model2
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4. inten_delta_model
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1. color5_delta_model0
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2. color5_delta_model1
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3. color5_delta_model2
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4. inten_delta_model
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Following the data for these Huffman tables is a single 1-bit code which
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indicates if the color endpoint codebook is grayscale or not.
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@@ -322,49 +322,49 @@ Immediately following this code is the compressed color endpoint codebook data.
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A simple form of DPCM coding is used to send the ETC1S intensity table indices and
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color values. Here is the procedure to decode the endpoint codebook:
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const int COLOR5_PAL0_PREV_HI = 9, COLOR5_PAL0_DELTA_LO = -9, COLOR5_PAL0_DELTA_HI = 31;
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const int COLOR5_PAL1_PREV_HI = 21, COLOR5_PAL1_DELTA_LO = -21, COLOR5_PAL1_DELTA_HI = 21;
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const int COLOR5_PAL2_PREV_HI = 31, COLOR5_PAL2_DELTA_LO = -31, COLOR5_PAL2_DELTA_HI = 9;
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const int COLOR5_PAL0_PREV_HI = 9, COLOR5_PAL0_DELTA_LO = -9, COLOR5_PAL0_DELTA_HI = 31;
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const int COLOR5_PAL1_PREV_HI = 21, COLOR5_PAL1_DELTA_LO = -21, COLOR5_PAL1_DELTA_HI = 21;
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const int COLOR5_PAL2_PREV_HI = 31, COLOR5_PAL2_DELTA_LO = -31, COLOR5_PAL2_DELTA_HI = 9;
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// Assume previous endpoint color is (16, 16, 16), and the previous intensity is 0.
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color32 prev_color5(16, 16, 16, 0);
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uint32_t prev_inten = 0;
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// Assume previous endpoint color is (16, 16, 16), and the previous intensity is 0.
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color32 prev_color5(16, 16, 16, 0);
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uint32_t prev_inten = 0;
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// For each endpoint codebook entry
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for (uint32_t i = 0; i < num_endpoints; i++)
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{
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// Decode the intensity delta Huffman code
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uint32_t inten_delta = sym_codec.decode_huffman(inten_delta_model);
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m_endpoints[i].m_inten5 = static_cast<uint8_t>((inten_delta + prev_inten) & 7);
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prev_inten = m_endpoints[i].m_inten5;
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// For each endpoint codebook entry
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for (uint32_t i = 0; i < num_endpoints; i++)
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{
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// Decode the intensity delta Huffman code
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uint32_t inten_delta = sym_codec.decode_huffman(inten_delta_model);
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m_endpoints[i].m_inten5 = static_cast<uint8_t>((inten_delta + prev_inten) & 7);
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prev_inten = m_endpoints[i].m_inten5;
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// Now decode the endpoint entry's color or intensity value
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for (uint32_t c = 0; c < (endpoints_are_grayscale ? 1U : 3U); c++)
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{
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// The Huffman table we used to decode the delta depends on the previous color's value
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int delta;
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if (prev_color5[c] <= basist::COLOR5_PAL0_PREV_HI)
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delta = sym_codec.decode_huffman(color5_delta_model0);
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else if (prev_color5[c] <= basist::COLOR5_PAL1_PREV_HI)
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delta = sym_codec.decode_huffman(color5_delta_model1);
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else
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delta = sym_codec.decode_huffman(color5_delta_model2);
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// Now decode the endpoint entry's color or intensity value
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for (uint32_t c = 0; c < (endpoints_are_grayscale ? 1U : 3U); c++)
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{
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// The Huffman table we used to decode the delta depends on the previous color's value
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int delta;
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if (prev_color5[c] <= basist::COLOR5_PAL0_PREV_HI)
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delta = sym_codec.decode_huffman(color5_delta_model0);
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else if (prev_color5[c] <= basist::COLOR5_PAL1_PREV_HI)
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delta = sym_codec.decode_huffman(color5_delta_model1);
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else
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delta = sym_codec.decode_huffman(color5_delta_model2);
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// Apply the delta
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int v = (prev_color5[c] + delta) & 31;
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// Apply the delta
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int v = (prev_color5[c] + delta) & 31;
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m_endpoints[i].m_color5[c] = static_cast<uint8_t>(v);
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m_endpoints[i].m_color5[c] = static_cast<uint8_t>(v);
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prev_color5[c] = static_cast<uint8_t>(v);
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}
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prev_color5[c] = static_cast<uint8_t>(v);
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}
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// If the endpoints are grayscale, set G and B to match R.
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if (endpoints_are_grayscale)
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{
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m_endpoints[i].m_color5[1] = m_endpoints[i].m_color5[0];
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m_endpoints[i].m_color5[2] = m_endpoints[i].m_color5[0];
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}
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}
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// If the endpoints are grayscale, set G and B to match R.
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if (endpoints_are_grayscale)
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{
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m_endpoints[i].m_color5[1] = m_endpoints[i].m_color5[0];
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m_endpoints[i].m_color5[2] = m_endpoints[i].m_color5[0];
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}
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}
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The rest of the section's data (if any) can be ignored.
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