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gamecom: fix for MULT instructions.

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This commit is contained in:
Robbbert 2016-05-21 11:08:45 +10:00
parent a2f6127830
commit 027d190447
1 changed files with 6 additions and 4 deletions
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10
src/devices/cpu/sm8500/sm85ops.h
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@ -1147,17 +1147,19 @@ case 0x4B: /* MOVW RRr,ww - 9 cycles - Flags affected: -------- */
mycycles += 9;
break;
case 0x4C: /* MULT Rrr,Rs - 24 cycles - Flags affected: -Z-0---- */
// operation is not known if r1 is odd, assuming same as even for now
ARG_RR;
res = mem_readword( r1 ) * mem_readbyte( r2 );
mem_writeword( r1, res & 0xFFFF );
res = mem_readbyte( r1 | 1 ) * mem_readbyte( r2 );
mem_writeword( r1 & 0xfe, res & 0xFFFF );
m_PS1 = m_PS1 & ~ ( FLAG_Z | FLAG_V );
m_PS1 |= ( ( res & 0xFFFF ) == 0x00 ? FLAG_Z : 0 );
mycycles += 24;
break;
case 0x4D: /* MULT RRr,i - 24 cycles - Flags affected: -Z-0---- */
// operation is not known if r1 is odd, assuming same as even for now
ARG_iR;
res = mem_readbyte( r1 + 1 ) * r2;
mem_writeword( r1, res & 0xFFFF );
res = mem_readbyte( r1 | 1 ) * r2;
mem_writeword( r1 & 0xfe, res & 0xFFFF );
m_PS1 = m_PS1 & ~ ( FLAG_Z | FLAG_V );
m_PS1 |= ( ( res & 0xFFFF ) == 0x00 ? FLAG_Z : 0 );
mycycles += 24;