MOTO_MAP_pack() : implements the optimized packing algorithm
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Thomas Bernard
parent
245b251a43
commit
830ba85329
@ -5361,16 +5361,24 @@ void Load_MOTO(T_IO_Context * context)
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}
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/**
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* Pack a stream of byte in the format used by Thomson MO/TO MAP files.
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*
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* - 00 cc xx yy .. : encodes a "copy run" (cc = bytes to copy)
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* - cc xx : encodes a "repeat run" (cc > 0 : count)
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*/
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#define MOTO_MAP_NOPACKING
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//#define MOTO_MAP_NOPACKING
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static unsigned int MOTO_MAP_pack(byte * packed, const byte * unpacked, unsigned int unpacked_len)
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{
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unsigned int src;
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unsigned int dst = 0;
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unsigned int repeat;
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unsigned int count;
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#ifndef MOTO_MAP_NOPACKING
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unsigned int repeat;
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unsigned int i;
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word * counts;
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#endif
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GFX2_Log(GFX2_DEBUG, "MOTO_MAP_pack(%p, %p, %u)\n", packed, unpacked, unpacked_len);
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if (unpacked_len == 0)
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return 0;
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if (unpacked_len == 1)
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@ -5398,9 +5406,12 @@ static unsigned int MOTO_MAP_pack(byte * packed, const byte * unpacked, unsigned
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src += count;
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return dst;
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#else
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counts = malloc(sizeof(word) * (unpacked_len + 1));
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i = 0;
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repeat = (unpacked[0] == unpacked[1]);
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count = 2;
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src = 2;
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// 1st step : count lenght of the Copy runs and Repeat runs
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while (src < unpacked_len)
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{
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if (repeat)
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@ -5409,9 +5420,8 @@ static unsigned int MOTO_MAP_pack(byte * packed, const byte * unpacked, unsigned
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count++;
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else
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{
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// flush run
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packed[dst++] = count;
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packed[dst++] = unpacked[src-1];
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// flush the repeat run
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counts[i++] = count | 0x8000; // 0x8000 is the marker for repeat runs
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count = 1;
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repeat = 0;
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}
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@ -5427,21 +5437,158 @@ static unsigned int MOTO_MAP_pack(byte * packed, const byte * unpacked, unsigned
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}
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else
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{
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// verifier le nombre de repetitions > 3
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if (unpacked[src] != unpacked[src+1] || unpacked[src] != unpacked[src+2])
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{
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src += 2;
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count += 3;
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}
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// flush the copy run
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counts[i++] = (count-1) | (count == 2 ? 0x8000 : 0); // mark copy run of 1 as repeat of 1
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count = 2;
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repeat = 1;
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}
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}
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src++;
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}
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// commit
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// flush the last run
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counts[i++] = ((repeat || count == 1) ? 0x8000 : 0) | count;
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counts[i++] = 0; // end marker
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// check consistency of counts
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count = 0;
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for (i = 0; counts[i] != 0; i++)
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count += (counts[i] & ~0x8000);
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if (count != unpacked_len)
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GFX2_Log(GFX2_ERROR, "*** encoding error in MOTO_MAP_pack() *** count=%u unpacked_len=%u\n",
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count, unpacked_len);
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// output optimized packed stream
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// repeat run are encoded cc xx
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// copy run are encoded 00 cc xx xx xx xx
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i = 0;
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src = 0;
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while (counts[i] != 0)
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{
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while (counts[i] & 0x8000) // repeat run
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{
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count = counts[i] & ~0x8000;
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GFX2_Log(GFX2_DEBUG, "MOTO_MAP_pack() %4u %4u repeat %u times %02x\n", src, i, count, unpacked[src]);
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while(count > 255)
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{
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packed[dst++] = 255;
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packed[dst++] = unpacked[src];
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count -= 255;
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src += 255;
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}
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packed[dst++] = count;
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packed[dst++] = unpacked[src];
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src += count;
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i++;
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}
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while (counts[i] != 0 && !(counts[i] & 0x8000)) // copy run
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{
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// calculate the "savings" of repeat runs between 2 copy run
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int savings = 0;
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unsigned int j;
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GFX2_Log(GFX2_DEBUG, "MOTO_MAP_pack() %4u %4u copy %u bytes\n", src, i, counts[i]);
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for (j = i + 1; counts[j] & 0x8000; j++) // check repeat runs until the next copy run
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{
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count = counts[j] & ~0x8000;
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if (savings < 0 && (savings + (int)count - 2) > 0)
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break;
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savings += count - 2; // a repeat run outputs 2 bytes for count bytes of input
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}
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count = counts[i];
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GFX2_Log(GFX2_DEBUG, " savings=%d i=%u j=%u (counts[j]=0x%04x)\n", savings, i, j, counts[j]);
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if (savings < 2 && (j > i + 1))
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{
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unsigned int k;
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if (counts[j] == 0) // go to the end of stream
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{
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for (k = i + 1; k < j; k++)
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count += (counts[k] & ~0x8000);
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GFX2_Log(GFX2_DEBUG, "MOTO_MAP_pack() src=%u extend copy from %u to %u\n", src, counts[i], count);
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i = j - 1;
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}
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else
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{
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for (k = i + 1; k < j; k++)
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count += (counts[k] & ~0x8000);
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if (!(counts[j] & 0x8000))
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{ // merge with the next copy run (and the repeat runs between)
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GFX2_Log(GFX2_DEBUG, "MOTO_MAP_pack() src=%u merge savings=%d\n", src, savings);
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i = j;
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counts[i] += count;
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continue;
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}
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else
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{ // merge with the next few repeat runs
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GFX2_Log(GFX2_DEBUG, "MOTO_MAP_pack() src=%u extends savings=%d\n", src, savings);
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i = j - 1;
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}
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}
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}
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while (count > 255)
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{
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packed[dst++] = 0;
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packed[dst++] = 255;
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memcpy(packed+dst, unpacked+src, 255);
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dst += 255;
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src += 255;
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count -= 255;
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}
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packed[dst++] = 0;
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packed[dst++] = count;
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memcpy(packed+dst, unpacked+src, count);
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dst += count;
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src += count;
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i++;
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}
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}
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free(counts);
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return dst;
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#endif
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}
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#if 0
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void Test_MOTO_MAP_pack(void)
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{
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unsigned int i, j;
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byte buffer[1024];
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byte buffer2[1024];
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unsigned int packed_len, unpacked_len, original_len;
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static const char * tests[] = {
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//"12345AAAAAAA@", // best : 00 05 "12345" 07 'A' 01 '@' : 11
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"123AABAA123@@@@@", // best : 00 0B "123AABAA123" 05 '@' : 15
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"123AAAAA123AABAA", // best : 00 03 "123" 05 'A' 00 06 "123AAB" 02 'A' : 17
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"123AAAAA123AAB", // best : 00 03 "123" 05 'A' 00 06 "123AAB" : 15
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"abcAABAAdddddddd", // best : 00 08 "abcAABAA" 08 'd' : 12
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NULL
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};
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GFX2_Log(GFX2_DEBUG, "Test_MOTO_MAP_pack\n");
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for (i = 0; tests[i]; i++)
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{
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original_len = strlen(tests[i]);
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packed_len = MOTO_MAP_pack(buffer, (const byte *)tests[i], original_len);
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GFX2_Log(GFX2_DEBUG, " %s (%u) packed to %u\n", tests[i], original_len, packed_len);
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unpacked_len = 0;
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j = 0;
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// unpack to test
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while (j < packed_len)
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{
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if (buffer[j] == 0)
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{ // copy
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memcpy(buffer2 + unpacked_len, buffer + j + 2, buffer[j+1]);
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unpacked_len += buffer[j+1];
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j += 2 + buffer[j+1];
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}
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else
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{ // repeat
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memset(buffer2 + unpacked_len, buffer[j+1], buffer[j]);
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unpacked_len += buffer[j];
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j += 2;
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}
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}
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if (unpacked_len != original_len || 0 != memcmp(tests[i], buffer2, original_len))
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GFX2_Log(GFX2_ERROR, "*** %u %s != %u %s ***\n", original_len, tests[i], unpacked_len, buffer2);
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}
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}
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#endif
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/**
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* GUI window to choose Thomson MO/TO saving parameters
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*
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