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// license:BSD-3-Clause
// copyright-holders:S. Smith,David Haywood
#include "emu.h"
#include "pcm2_prot.h"
extern const device_type PCM2_PROT = &device_creator<pcm2_prot_device>;
pcm2_prot_device::pcm2_prot_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
: device_t(mconfig, PCM2_PROT, "NeoGeo Protection (NEOPCM2)", tag, owner, clock, "pcm2_prot", __FILE__)
{
}
void pcm2_prot_device::device_start()
{
}
void pcm2_prot_device::device_reset()
{
}
/***************************************************************************
NeoGeo 'V' (PCM) ROM encryption
NEOPCM2 chip
***************************************************************************/
/* Neo-Pcm2 Drivers for Encrypted V Roms */
void pcm2_prot_device::neo_pcm2_snk_1999(UINT8* ymrom, UINT32 ymsize, int value)
{ /* thanks to Elsemi for the NEO-PCM2 info */
UINT16 *rom = (UINT16 *)ymrom;
int size = ymsize;
int i, j;
if( rom != NULL )
{ /* swap address lines on the whole ROMs */
std::vector<UINT16> buffer(value / 2);
for( i = 0; i < size / 2; i += ( value / 2 ) )
{
memcpy( &buffer[0], &rom[ i ], value );
for( j = 0; j < (value / 2); j++ )
{
rom[ i + j ] = buffer[ j ^ (value/4) ];
}
}
}
}
/* the later PCM2 games have additional scrambling */
void pcm2_prot_device::neo_pcm2_swap(UINT8* ymrom, UINT32 ymsize, int value)
{
static const UINT32 addrs[7][2]={
{0x000000,0xa5000},
{0xffce20,0x01000},
{0xfe2cf6,0x4e001},
{0xffac28,0xc2000},
{0xfeb2c0,0x0a000},
{0xff14ea,0xa7001},
{0xffb440,0x02000}};
static const UINT8 xordata[7][8]={
{0xf9,0xe0,0x5d,0xf3,0xea,0x92,0xbe,0xef},
{0xc4,0x83,0xa8,0x5f,0x21,0x27,0x64,0xaf},
{0xc3,0xfd,0x81,0xac,0x6d,0xe7,0xbf,0x9e},
{0xc3,0xfd,0x81,0xac,0x6d,0xe7,0xbf,0x9e},
{0xcb,0x29,0x7d,0x43,0xd2,0x3a,0xc2,0xb4},
{0x4b,0xa4,0x63,0x46,0xf0,0x91,0xea,0x62},
{0x4b,0xa4,0x63,0x46,0xf0,0x91,0xea,0x62}};
dynamic_buffer buf(0x1000000);
int i, j, d;
UINT8* src = ymrom;
memcpy(&buf[0],src,0x1000000);
for (i=0;i<0x1000000;i++)
{
j=BITSWAP24(i,23,22,21,20,19,18,17,0,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,16);
j=j^addrs[value][1];
d=((i+addrs[value][0])&0xffffff);
src[j]=buf[d]^xordata[value][j&0x7];
}
}
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