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Unpletter
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Port the changes and fixes to the C version.

This commit is contained in:
Sylvain Glaize 2024-02-22 19:48:55 +01:00
parent 82f4d5e2f1
commit a350b7f94e
1 changed files with 46 additions and 9 deletions
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55
unpletter/unpletter_c.c
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@ -1,3 +1,4 @@
#include <stdbool.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
@ -33,9 +34,9 @@ data_type getBit(struct Uncompressor* uncompressor)
return bit; return bit;
} }
data_type getInterlacedEliasGamma(struct Uncompressor* uncompressor) int getInterlacedEliasGamma(struct Uncompressor* uncompressor)
{ {
data_type value = 1; int value = 1;
while (getBit(uncompressor)) while (getBit(uncompressor))
{ {
value = (value << 1) | getBit(uncompressor); value = (value << 1) | getBit(uncompressor);
@ -43,23 +44,41 @@ data_type getInterlacedEliasGamma(struct Uncompressor* uncompressor)
return value; return value;
} }
void uncompress(struct Uncompressor* uncompressor, size_t in_data_length) unsigned char * realloc_output(unsigned char * output, size_t output_position, size_t * output_max_size, size_t add_data_size)
{ {
unsigned char* output = (unsigned char*) malloc(in_data_length * 3);// * 3 is an arbitrary number... if (output_position + add_data_size > *output_max_size)
{
*output_max_size *= 2;
output = (unsigned char*) realloc(output, *output_max_size);
}
return output;
}
void uncompress(struct Uncompressor* uncompressor, size_t in_data_length, bool dsk2rom_tweak)
{
unsigned char* output = (unsigned char*) malloc(in_data_length);// * 10 is an arbitrary number...
size_t output_max_size = in_data_length;
size_t output_position = 0; size_t output_position = 0;
int q_value = (getBit(uncompressor) << 2 | getBit(uncompressor) << 1 | getBit(uncompressor)) + 1; // The dsk2rom version has a fixed value of 2 for q_value and doesn't read it from the compressed variable stream
int q_value = 2;
if (!dsk2rom_tweak)
{
q_value = (getBit(uncompressor) << 2 | getBit(uncompressor) << 1 | getBit(uncompressor)) + 1;
}
data_type first_byte = getByte(uncompressor); data_type first_byte = getByte(uncompressor);
output[output_position++] = first_byte; output[output_position++] = first_byte;
uncompressor->dataPosition = dsk2rom_tweak ? 1 : 2;
while (uncompressor->dataPosition < in_data_length) while (uncompressor->dataPosition < in_data_length)
{ {
if (getBit(uncompressor)) if (getBit(uncompressor))
{ {
data_type length = getInterlacedEliasGamma(uncompressor) + 1; int length = getInterlacedEliasGamma(uncompressor) + 1;
if (length == 255) if (length == 262143 || (dsk2rom_tweak && length == 131072))
{ {
break; break;
} }
@ -70,6 +89,8 @@ void uncompress(struct Uncompressor* uncompressor, size_t in_data_length)
offset = offset & 0x7F; offset = offset & 0x7F;
switch (q_value) switch (q_value)
{ {
case 7:
offset = offset | (getBit(uncompressor) << 13);
case 6: case 6:
offset = offset | (getBit(uncompressor) << 12); offset = offset | (getBit(uncompressor) << 12);
case 5: case 5:
@ -91,22 +112,38 @@ void uncompress(struct Uncompressor* uncompressor, size_t in_data_length)
} }
offset += 1; offset += 1;
output = realloc_output(output, output_position, &output_max_size, length);
for (int i = 0; i < length; i++) for (int i = 0; i < length; i++)
{ {
// Realloc if necessary
if (output_position + 1 > output_max_size)
{
output_max_size *= 2;
output = (unsigned char*) realloc(output, output_max_size);
}
output[output_position] = output[output_position - offset]; output[output_position] = output[output_position - offset];
output_position += 1; output_position += 1;
} }
} }
else else
{ {
output = realloc_output(output, output_position, &output_max_size, 1);
output[output_position++] = getByte(uncompressor); output[output_position++] = getByte(uncompressor);
} }
} }
int count = 0;
for (int i = 0; i < output_position; i++) for (int i = 0; i < output_position; i++)
{ {
printf("%c", output[i]); printf("%02x ", output[i]);
if (++count % 30 == 0)
{
printf("\n");
}
} }
printf("\n");
printf("Output size: %zu\n", output_position);
free(output); free(output);
} }
@ -137,7 +174,7 @@ int main(int argc, char* argv[])
} }
struct Uncompressor uncompressor = {compressedData, 0, 0, 7}; struct Uncompressor uncompressor = {compressedData, 0, 0, 7};
uncompress(&uncompressor, length); uncompress(&uncompressor, length, true);
free(compressedData); free(compressedData);
fclose(file); fclose(file);