MESS SVN History

15994 Revisions

r14325 Friday 3rd February, 2012 at 07:22:39 UTC by Miodrag Milanović
-lynx: cartslot changed to mandatory (real lynx will not power on without a game inserted) [Huygens] moved sign detection back outside multiply function. added sign flag updating on write to LSB of MATH_CD register.

[src/mess/machine]

lynx.c

src/mess/machine/lynx.c
r14324	r14325
882	882	Accumulate JKLM
883	883	*/
884	884	state->m_suzy.accumulate_overflow = FALSE;
885
886		if (state->m_suzy.signed_math)
887		{
888		UINT16 factor, temp;
889		factor = state->m_suzy.data[MATH_B] \| (state->m_suzy.data[MATH_A] << 8);
890		if ((factor - 1) & 0x8000) /* here we use -1 to cover the math bugs on the sign of 0 and 0x8000 */
891		{
892		temp = (factor ^ 0xffff) + 1;
893		state->m_sign_AB = - 1;
894		state->m_suzy.data[MATH_B] = temp & 0xff;
895		state->m_suzy.data[MATH_A] = temp >> 8;
896		}
897		else
898		state->m_sign_AB = 1;
899
900		factor = state->m_suzy.data[MATH_D] \| (state->m_suzy.data[MATH_C] << 8);
901		if ((factor - 1) & 0x8000) /* here we use -1 to cover the math bugs on the sign of 0 and 0x8000 */
902		{
903		temp = (factor ^ 0xffff) + 1;
904		state->m_sign_CD = - 1;
905		state->m_suzy.data[MATH_D] = temp & 0xff;
906		state->m_suzy.data[MATH_C] = temp >> 8;
907		}
908		else
909		state->m_sign_CD = 1;
910		}
911	885
912	886	left = state->m_suzy.data[MATH_B] \| (state->m_suzy.data[MATH_A] << 8);
913	887	right = state->m_suzy.data[MATH_D] \| (state->m_suzy.data[MATH_C] << 8);
r14324	r14325
1229	1203	case MATH_M:
1230	1204	state->m_suzy.accumulate_overflow = FALSE;
1231	1205	break;
	1206	case MATH_C:
	1207	/* If we are going to perform a signed multiplication, we store the sign and convert the number
	1208	to an unsigned one */
	1209	if (state->m_suzy.signed_math)
	1210	{
	1211	UINT16 factor, temp;
	1212	factor = state->m_suzy.data[MATH_D] \| (state->m_suzy.data[MATH_C] << 8);
	1213	if ((factor - 1) & 0x8000) /* here we use -1 to cover the math bugs on the sign of 0 and 0x8000 */
	1214	{
	1215	temp = (factor ^ 0xffff) + 1;
	1216	state->m_sign_CD = - 1;
	1217	state->m_suzy.data[MATH_D] = temp & 0xff;
	1218	state->m_suzy.data[MATH_C] = temp >> 8;
	1219	}
	1220	else
	1221	state->m_sign_CD = 1;
	1222	}
	1223	break;
	1224	case MATH_D:
	1225	/* Documentation states that writing to the MATH_D will set MATH_C to zero but not update the sign flag.
	1226	Implementing the sign detection as described in the documentation causes Stun Runners to not work.
	1227	Either the sign error in the docs is not as described or writing to the lower byte does update the sign flag.
	1228	Here I assume the sign flag gets updated. */
	1229	if (data)
	1230	state->m_sign_CD = 1;
	1231	break;
1232	1232	/* Writing to A will start a 16 bit multiply */
1233	1233	/* If we are going to perform a signed multiplication, we also store the sign and convert the
1234	1234	number to an unsigned one */
1235	1235	case MATH_A:
	1236	if (state->m_suzy.signed_math)
	1237	{
	1238	UINT16 factor, temp;
	1239	factor = state->m_suzy.data[MATH_B] \| (state->m_suzy.data[MATH_A] << 8);
	1240	if ((factor - 1) & 0x8000) /* here we use -1 to cover the math bugs on the sign of 0 and 0x8000 */
	1241	{
	1242	temp = (factor ^ 0xffff) + 1;
	1243	state->m_sign_AB = - 1;
	1244	state->m_suzy.data[MATH_B] = temp & 0xff;
	1245	state->m_suzy.data[MATH_A] = temp >> 8;
	1246	}
	1247	else
	1248	state->m_sign_AB = 1;
	1249	}
1236	1250	lynx_multiply(state);
1237	1251	break;
1238	1252	/* Writing to E will start a 16 bit divide */
r14324	r14325
1932	1946	state->m_mikey.data[0x90] = 0x00;
1933	1947	state->m_mikey.data[0x92] = 0x00;
1934	1948
1935		/*
1936		state->m_suzy.data[MATH_A] = 0xff;
1937		state->m_suzy.data[MATH_B] = 0xff;
1938		state->m_suzy.data[MATH_C] = 0xff;
1939		state->m_suzy.data[MATH_D] = 0xff;
1940
1941		state->m_suzy.data[MATH_E] = 0xff;
1942		state->m_suzy.data[MATH_F] = 0xff;
1943		state->m_suzy.data[MATH_G] = 0xff;
1944		state->m_suzy.data[MATH_H] = 0xff;
1945
1946		state->m_suzy.data[MATH_J] = 0xff;
1947		state->m_suzy.data[MATH_K] = 0xff;
1948		state->m_suzy.data[MATH_L] = 0xff;
1949		state->m_suzy.data[MATH_M] = 0xff;
1950		state->m_suzy.data[MATH_P] = 0xff;
1951		*/
1952
1953	1949	lynx_uart_reset(state);
1954	1950
1955	1951	// hack to allow current object loading to work
r14324	r14325
2131	2127	MACHINE_CONFIG_FRAGMENT(lynx_cartslot)
2132	2128	MCFG_CARTSLOT_ADD("cart")
2133	2129	MCFG_CARTSLOT_EXTENSION_LIST("lnx,lyx")
2134		MCFG_CARTSLOT_~~NOT_~~MANDATORY
	2130	MCFG_CARTSLOT_MANDATORY
2135	2131	MCFG_CARTSLOT_INTERFACE("lynx_cart")
2136	2132	MCFG_CARTSLOT_LOAD(lynx_cart)
2137	2133	MCFG_CARTSLOT_PARTIALHASH(lynx_partialhash)

15994 Revisions