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author | Max Horn | 2011-04-13 11:24:41 +0200 |
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committer | Max Horn | 2011-04-13 11:49:24 +0200 |
commit | 29962bfc73879845da8c58e31f75d53ff51bd10b (patch) | |
tree | 7df88eaf4676488e93dc8168b25f9fefb36a54e8 /engines/scumm/imuse_digi/dimuse_codecs.cpp | |
parent | 79f514a397c9e558e25a28fa5f92a02f42d7828a (diff) | |
download | scummvm-rg350-29962bfc73879845da8c58e31f75d53ff51bd10b.tar.gz scummvm-rg350-29962bfc73879845da8c58e31f75d53ff51bd10b.tar.bz2 scummvm-rg350-29962bfc73879845da8c58e31f75d53ff51bd10b.zip |
SCUMM: Move ADPCM decoder into separate function
Diffstat (limited to 'engines/scumm/imuse_digi/dimuse_codecs.cpp')
-rw-r--r-- | engines/scumm/imuse_digi/dimuse_codecs.cpp | 254 |
1 files changed, 127 insertions, 127 deletions
diff --git a/engines/scumm/imuse_digi/dimuse_codecs.cpp b/engines/scumm/imuse_digi/dimuse_codecs.cpp index 62a006c56b..99fff4e4c3 100644 --- a/engines/scumm/imuse_digi/dimuse_codecs.cpp +++ b/engines/scumm/imuse_digi/dimuse_codecs.cpp @@ -183,8 +183,133 @@ static int32 compDecode(byte *src, byte *dst) { } #undef NextBit +int32 decompressADPCM(byte *compInput, byte *compOutput, int channels) { + byte *src; + + // Decoder for the the IMA ADPCM variants used in COMI. + // Contrary to regular IMA ADPCM, this codec uses a variable + // bitsize for the encoded data. + + const int MAX_CHANNELS = 2; + int32 outputSamplesLeft; + int32 destPos; + int16 firstWord; + byte initialTablePos[MAX_CHANNELS] = {0, 0}; + //int32 initialimcTableEntry[MAX_CHANNELS] = {7, 7}; + int32 initialOutputWord[MAX_CHANNELS] = {0, 0}; + int32 totalBitOffset, curTablePos, outputWord; + byte *dst; + int i; + + // We only support mono and stereo + assert(channels == 1 || channels == 2); + + src = compInput; + dst = compOutput; + outputSamplesLeft = 0x1000; + + // Every data packet contains 0x2000 bytes of audio data + // when extracted. In order to encode bigger data sets, + // one has to split the data into multiple blocks. + // + // Every block starts with a 2 byte word. If that word is + // non-zero, it indicates the size of a block of raw audio + // data (not encoded) following it. That data we simply copy + // to the output buffer and the proceed by decoding the + // remaining data. + // + // If on the other hand the word is zero, then what follows + // are 7*channels bytes containing seed data for the decoder. + firstWord = READ_BE_UINT16(src); + src += 2; + if (firstWord != 0) { + // Copy raw data + memcpy(dst, src, firstWord); + dst += firstWord; + src += firstWord; + assert((firstWord & 1) == 0); + outputSamplesLeft -= firstWord / 2; + } else { + // Read the seed values for the decoder. + for (i = 0; i < channels; i++) { + initialTablePos[i] = *src; + src += 1; + //initialimcTableEntry[i] = READ_BE_UINT32(src); + src += 4; + initialOutputWord[i] = READ_BE_UINT32(src); + src += 4; + } + } + + totalBitOffset = 0; + // The channels are encoded separately. + for (int chan = 0; chan < channels; chan++) { + // Read initial state (this makes it possible for the data stream + // to be split & spread across multiple data chunks. + curTablePos = initialTablePos[chan]; + //imcTableEntry = initialimcTableEntry[chan]; + outputWord = initialOutputWord[chan]; + + // We need to interleave the channels in the output; we achieve + // that by using a variables dest offset: + destPos = chan * 2; + + const int bound = (channels == 1) + ? outputSamplesLeft + : ((chan == 0) + ? (outputSamplesLeft+1) / 2 + : outputSamplesLeft / 2); + for (i = 0; i < bound; ++i) { + // Determine the size (in bits) of the next data packet + const int32 curTableEntryBitCount = _imcTableEntryBitCount[curTablePos]; + assert(2 <= curTableEntryBitCount && curTableEntryBitCount <= 7); + + // Read the next data packet + const byte *readPos = src + (totalBitOffset >> 3); + const uint16 readWord = (uint16)(READ_BE_UINT16(readPos) << (totalBitOffset & 7)); + const byte packet = (byte)(readWord >> (16 - curTableEntryBitCount)); + + // Advance read position to the next data packet + totalBitOffset += curTableEntryBitCount; + + // Decode the data packet into a delta value for the output signal. + const byte signBitMask = (1 << (curTableEntryBitCount - 1)); + const byte dataBitMask = (signBitMask - 1); + const byte data = (packet & dataBitMask); + + int32 delta = imcTable[curTablePos] * (2 * data + 1) >> (curTableEntryBitCount - 1); + + // The topmost bit in the data packet tells is a sign bit + if ((packet & signBitMask) != 0) { + delta = -delta; + } + + // Accumulate the delta onto the output data + outputWord += delta; + + // Clip outputWord to 16 bit signed, and write it into the destination stream + if (outputWord > 0x7fff) + outputWord = 0x7fff; + if (outputWord < -0x8000) + outputWord = -0x8000; + WRITE_BE_UINT16(dst + destPos, outputWord); + destPos += channels << 1; + + // Adjust the curTablePos + curTablePos += (int8)imxOtherTable[curTableEntryBitCount - 2][data]; + if (curTablePos < 0) + curTablePos = 0; + else if (curTablePos >= ARRAYSIZE(imcTable)) + curTablePos = ARRAYSIZE(imcTable) - 1; + } + } + + return 0x2000; +} + + int32 decompressCodec(int32 codec, byte *compInput, byte *compOutput, int32 inputSize) { - int32 outputSize, channels; + int32 outputSize; int32 offset1, offset2, offset3, length, k, c, s, j, r, t, z; byte *src, *t_table, *p, *ptr; byte t_tmp1, t_tmp2; @@ -506,132 +631,7 @@ int32 decompressCodec(int32 codec, byte *compInput, byte *compOutput, int32 inpu case 13: case 15: - if (codec == 13) { - channels = 1; - } else { - channels = 2; - } - - { - // Decoder for the the IMA ADPCM variants used in COMI. - // Contrary to regular IMA ADPCM, this codec uses a variable - // bitsize for the encoded data. - - const int MAX_CHANNELS = 2; - int32 outputSamplesLeft; - int32 destPos; - int16 firstWord; - byte initialTablePos[MAX_CHANNELS] = {0, 0}; - //int32 initialimcTableEntry[MAX_CHANNELS] = {7, 7}; - int32 initialOutputWord[MAX_CHANNELS] = {0, 0}; - int32 totalBitOffset, curTablePos, outputWord; - byte *dst; - int i; - - // We only support mono and stereo - assert(channels == 1 || channels == 2); - - src = compInput; - dst = compOutput; - outputSize = 0x2000; - outputSamplesLeft = 0x1000; - - // Every data packet contains 0x2000 bytes of audio data - // when extracted. In order to encode bigger data sets, - // one has to split the data into multiple blocks. - // - // Every block starts with a 2 byte word. If that word is - // non-zero, it indicates the size of a block of raw audio - // data (not encoded) following it. That data we simply copy - // to the output buffer and the proceed by decoding the - // remaining data. - // - // If on the other hand the word is zero, then what follows - // are 7*channels bytes containing seed data for the decoder. - firstWord = READ_BE_UINT16(src); - src += 2; - if (firstWord != 0) { - // Copy raw data - memcpy(dst, src, firstWord); - dst += firstWord; - src += firstWord; - assert((firstWord & 1) == 0); - outputSamplesLeft -= firstWord / 2; - } else { - // Read the seed values for the decoder. - for (i = 0; i < channels; i++) { - initialTablePos[i] = *src; - src += 1; - //initialimcTableEntry[i] = READ_BE_UINT32(src); - src += 4; - initialOutputWord[i] = READ_BE_UINT32(src); - src += 4; - } - } - - totalBitOffset = 0; - // The channels are encoded separately. - for (int chan = 0; chan < channels; chan++) { - // Read initial state (this makes it possible for the data stream - // to be split & spread across multiple data chunks. - curTablePos = initialTablePos[chan]; - //imcTableEntry = initialimcTableEntry[chan]; - outputWord = initialOutputWord[chan]; - - // We need to interleave the channels in the output; we achieve - // that by using a variables dest offset: - destPos = chan * 2; - - const int bound = (channels == 1) - ? outputSamplesLeft - : ((chan == 0) - ? (outputSamplesLeft+1) / 2 - : outputSamplesLeft / 2); - for (i = 0; i < bound; ++i) { - // Determine the size (in bits) of the next data packet - const int32 curTableEntryBitCount = _imcTableEntryBitCount[curTablePos]; - assert(2 <= curTableEntryBitCount && curTableEntryBitCount <= 7); - - // Read the next data packet - const byte *readPos = src + (totalBitOffset >> 3); - const uint16 readWord = (uint16)(READ_BE_UINT16(readPos) << (totalBitOffset & 7)); - const byte packet = (byte)(readWord >> (16 - curTableEntryBitCount)); - - // Advance read position to the next data packet - totalBitOffset += curTableEntryBitCount; - - // Decode the data packet into a delta value for the output signal. - const byte signBitMask = (1 << (curTableEntryBitCount - 1)); - const byte dataBitMask = (signBitMask - 1); - const byte data = (packet & dataBitMask); - - int32 delta = imcTable[curTablePos] * (2 * data + 1) >> (curTableEntryBitCount - 1); - - // The topmost bit in the data packet tells is a sign bit - if ((packet & signBitMask) != 0) { - delta = -delta; - } - - // Accumulate the delta onto the output data - outputWord += delta; - - // Clip outputWord to 16 bit signed, and write it into the destination stream - if (outputWord > 0x7fff) - outputWord = 0x7fff; - if (outputWord < -0x8000) - outputWord = -0x8000; - WRITE_BE_UINT16(dst + destPos, outputWord); - destPos += channels << 1; - - // Adjust the curTablePos - curTablePos += (int8)imxOtherTable[curTableEntryBitCount - 2][data]; - if (curTablePos < 0) - curTablePos = 0; - else if (curTablePos >= ARRAYSIZE(imcTable)) - curTablePos = ARRAYSIZE(imcTable) - 1; - } - } - } + outputSize = decompressADPCM(compInput, compOutput, (codec == 13) ? 1 : 2); break; default: |