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bug: fix decompress word fill issue

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* decompression on vanilla 1mb ROMs was having issues
This commit is contained in:
scawful
2022-08-17 16:55:08 -04:00
parent f3eb31766a
commit 5d0a381b00
1 changed files with 25 additions and 21 deletions
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46
src/app/rom.cc
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@@ -499,43 +499,47 @@ absl::StatusOr<Bytes> ROM::Decompress(int offset, int size, bool reversed) {
Bytes buffer(size, 0);
uint length = 0;
uint buffer_pos = 0;
uchar cmd = 0;
uchar databyte = rom_data_[offset];
while (databyte != SNES_BYTE_MAX) { // End of decompression
if ((databyte & CMD_EXPANDED_MOD) == CMD_EXPANDED_MOD) {
uchar command = 0;
uchar header = rom_data_[offset];
while (header != SNES_BYTE_MAX) {
if ((header & CMD_EXPANDED_MOD) == CMD_EXPANDED_MOD) {
// Expanded Command
cmd = ((databyte >> 2) & CMD_MOD);
command = ((header >> 2) & CMD_MOD);
length =
(((databyte << 8) | rom_data_[offset + 1]) & CMD_EXPANDED_LENGTH_MOD);
(((header << 8) | rom_data_[offset + 1]) & CMD_EXPANDED_LENGTH_MOD);
offset += 2; // Advance 2 bytes in ROM
} else {
// Normal Command
cmd = ((databyte >> 5) & CMD_MOD);
length = (databyte & CMD_NORMAL_LENGTH_MOD);
command = ((header >> 5) & CMD_MOD);
length = (header & CMD_NORMAL_LENGTH_MOD);
offset += 1; // Advance 1 byte in ROM
}
length += 1; // each commands is at least of size 1 even if index 00
switch (cmd) {
switch (command) {
case kCommandDirectCopy: // Does not advance in the ROM
memcpy(buffer.data() + buffer_pos, rom_data_.data() + offset, length);
buffer_pos += length;
offset += length;
break;
case kCommandByteFill:
for (int i = 0; i < length; i++)
buffer[buffer_pos++] = rom_data_[offset];
offset += 1; // Advances 1 byte in the ROM
break;
case kCommandWordFill:
for (int i = 0; i < length; i += 2) {
for (int i = 0; i < length; i++) {
buffer[buffer_pos] = rom_data_[offset];
buffer_pos++;
buffer[buffer_pos] = rom_data_[offset + 1];
buffer_pos++;
}
offset += 2; // Advance 2 byte in the ROM
offset += 1; // Advances 1 byte in the ROM
break;
case kCommandWordFill: {
auto a = rom_data_[offset + 1];
auto b = rom_data_[offset + 2];
for (int i = 0; i < length; i = i + 2) {
buffer[buffer_pos + i] = a;
if ((i + 1) < length) buffer[buffer_pos + i + 1] = b;
}
buffer_pos += length;
offset += 2; // Advance 2 byte in the ROM
} break;
case kCommandIncreasingFill: {
uchar inc_byte = rom_data_[offset];
for (int i = 0; i < length; i++) {
@@ -574,11 +578,11 @@ absl::StatusOr<Bytes> ROM::Decompress(int offset, int size, bool reversed) {
std::cout << absl::StrFormat(
"DecompressOverworld: Invalid command in header for "
"decompression (Offset : %#06x, Command: %#04x)\n",
offset, cmd);
offset, command);
} break;
}
// check next byte
databyte = rom_data_[offset];
// check next byte
header = rom_data_[offset];
}
return buffer;