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fix decompression case for twcup98 title screen (nw)

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This commit is contained in:
mamehaze 2015-01-22 10:27:42 +00:00
parent 8f12e637d4
commit d6cbabce5c
2 changed files with 31 additions and 6 deletions
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33
src/mame/machine/315-5881_crypt.c
View File

@ -70,8 +70,15 @@ UINT16 sega_315_5881_crypt_device::do_decrypt(UINT8 *&base)
if(!enc_ready)
enc_start();
if(dec_header & FLAG_COMPRESSED) {
if(line_buffer_pos == line_buffer_size)
if (line_buffer_pos == line_buffer_size) // if there's no data left to read..
{
if (done_compression == 1)
enc_start();
line_fill();
}
base = line_buffer + line_buffer_pos;
line_buffer_pos += 2;
} else {
@ -94,6 +101,9 @@ void sega_315_5881_crypt_device::set_addr_high(UINT16 data)
{
prot_cur_address = (prot_cur_address & 0x0000ffff) | (data << 16);
enc_ready = false;
buffer_bit = 7;
buffer_bit2 = 15;
}
void sega_315_5881_crypt_device::set_subkey(UINT16 data)
@ -645,16 +655,29 @@ UINT16 sega_315_5881_crypt_device::get_decrypted_16()
prot_cur_address ++;
// printf("get_decrypted_16 %04x\n", res);
return res;
}
void sega_315_5881_crypt_device::enc_start()
{
dec_hist = 0; // seems to be needed by astrass at least otherwise any call after the first one will be influenced by the one before it.
block_pos = 0;
done_compression = 0;
buffer_pos = BUFFER_SIZE;
if (buffer_bit2 != 15) // if we have remaining bits in the decompression buffer we shouldn't read the next word yet but should instead use the bits we have?? (twcup98) (might just be because we should be pulling bytes not words?)
{
// printf("buffer_bit2 is %d\n", buffer_bit2);
dec_header = (buffer2a & 0x0003) << 16;
}
else
{
dec_hist = 0; // seems to be needed by astrass at least otherwise any call after the first one will be influenced by the one before it.
dec_header = get_decrypted_16() << 16;
}
dec_header |= get_decrypted_16();
// the lower header bits are 2 values that multiply together to get the current stream length
@ -782,7 +805,7 @@ int sega_315_5881_crypt_device::get_compressed_bit()
if (buffer_bit2 == 15)
{
buffer_bit2 = 0;
UINT16 buffer2a = get_decrypted_16();
buffer2a = get_decrypted_16();
buffer2[0] = buffer2a;
buffer2[1] = buffer2a >> 8;
// block_pos+=2;
@ -857,12 +880,12 @@ void sega_315_5881_crypt_device::line_fill()
}
}
block_pos++;
if (block_numlines == block_pos)
{
enc_start();
done_compression = 1;
}
else
{
block_pos++;
}
}

2
src/mame/machine/315-5881_crypt.h
View File

@ -58,10 +58,12 @@ private:
int buffer_pos, line_buffer_pos, line_buffer_size, buffer_bit, buffer_bit2;
UINT8 buffer2[2];
UINT16 buffer2a;
int block_size;
int block_pos;
int block_numlines;
int done_compression;
struct sbox {
UINT8 table[64];