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neogeo/prot_cmc.cpp: Use util::sum16_creator

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This commit is contained in:
AJR 2024-01-08 21:56:09 -05:00
parent cd6793407d
commit 023dc919e7
2 changed files with 3 additions and 14 deletions
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16
src/devices/bus/neogeo/prot_cmc.cpp
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@ -661,18 +661,6 @@ static const uint8_t m1_address_0_7_xor[256] =
}; };
/* The CMC50 hardware does a checksum of the first 64kb of the M1 rom, and
uses this checksum as the basis of the key with which to decrypt the rom */
uint16_t cmc_prot_device::generate_cs16(uint8_t *rom, int size)
{
uint16_t cs16 = 0x0000;
for (int i = 0; i < size; i++)
cs16 += rom[i];
return cs16 & 0xffff;
}
int cmc_prot_device::m1_address_scramble(int address, uint16_t key) int cmc_prot_device::m1_address_scramble(int address, uint16_t key)
{ {
const int p1[8][16] = { const int p1[8][16] = {
@ -711,7 +699,9 @@ void cmc_prot_device::cmc50_m1_decrypt(uint8_t* romcrypt, uint32_t romcrypt_size
std::vector<uint8_t> buffer(rom_size); std::vector<uint8_t> buffer(rom_size);
uint16_t key = generate_cs16(rom, 0x10000); /* The CMC50 hardware does a checksum of the first 64kb of the M1 rom, and
uses this checksum as the basis of the key with which to decrypt the rom */
uint16_t key = util::sum16_creator::simple(rom, 0x10000);
//printf("key %04x\n",key); //printf("key %04x\n",key);

1
src/devices/bus/neogeo/prot_cmc.h
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@ -59,7 +59,6 @@ public:
void sfix_decrypt(uint8_t* rom, uint32_t rom_size, uint8_t* fixed, uint32_t fixed_size); void sfix_decrypt(uint8_t* rom, uint32_t rom_size, uint8_t* fixed, uint32_t fixed_size);
uint16_t generate_cs16(uint8_t *rom, int size);
int m1_address_scramble(int address, uint16_t key); int m1_address_scramble(int address, uint16_t key);
void cmc50_m1_decrypt(uint8_t* romcrypt, uint32_t romcrypt_size, uint8_t* romaudio, uint32_t romaudio_size); void cmc50_m1_decrypt(uint8_t* romcrypt, uint32_t romcrypt_size, uint8_t* romaudio, uint32_t romaudio_size);