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i386: improved handling of override prefixes after a rep instruction [Gabriele Gorla]

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This commit is contained in:
Michaël Banaan Ananas 2009-09-14 12:30:36 +00:00
parent d14a2d2c32
commit d84af18926
1 changed files with 49 additions and 18 deletions
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67
src/emu/cpu/i386/i386ops.c
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@ -1016,31 +1016,62 @@ static void I386OP(repeat)(i386_state *cpustate, int invert_flag)
{
UINT32 repeated_eip = cpustate->eip;
UINT32 repeated_pc = cpustate->pc;
UINT8 opcode = FETCH(cpustate);
UINT8 opcode; // = FETCH(cpustate);
UINT32 eas, ead;
UINT32 count;
INT32 cycle_base = 0, cycle_adjustment = 0;
UINT8 prefix_flag=1;
UINT8 *flag = NULL;
if( cpustate->segment_prefix ) {
eas = i386_translate(cpustate, cpustate->segment_override, cpustate->sreg[CS].d ? REG32(ESI) : REG16(SI) );
} else {
eas = i386_translate(cpustate, DS, cpustate->sreg[CS].d ? REG32(ESI) : REG16(SI) );
}
ead = i386_translate(cpustate, ES, cpustate->sreg[CS].d ? REG32(EDI) : REG16(DI) );
if( opcode == 0x66 ) {
do {
repeated_eip = cpustate->eip;
repeated_pc = cpustate->pc;
opcode = FETCH(cpustate);
switch(opcode) {
case 0x26:
cpustate->segment_override=1;
cpustate->segment_prefix=ES;
break;
case 0x2e:
cpustate->segment_override=1;
cpustate->segment_prefix=CS;
break;
case 0x36:
cpustate->segment_override=1;
cpustate->segment_prefix=SS;
break;
case 0x3e:
cpustate->segment_override=1;
cpustate->segment_prefix=DS;
break;
case 0x64:
cpustate->segment_override=1;
cpustate->segment_prefix=FS;
break;
case 0x65:
cpustate->segment_override=1;
cpustate->segment_prefix=GS;
break;
case 0x66:
cpustate->operand_size ^= 1;
repeated_eip = cpustate->eip;
repeated_pc = cpustate->pc;
opcode = FETCH(cpustate);
}
if( opcode == 0x67 ) {
break;
case 0x67:
cpustate->address_size ^= 1;
repeated_eip = cpustate->eip;
repeated_pc = cpustate->pc;
opcode = FETCH(cpustate);
break;
default:
prefix_flag=0;
}
} while (prefix_flag);
if( cpustate->segment_prefix ) {
// FIXME: the following does not work if both address override and segment override are used
eas = i386_translate(cpustate, cpustate->segment_override, cpustate->sreg[cpustate->segment_prefix].d ? REG32(ESI) : REG16(SI) );
} else {
eas = i386_translate(cpustate, DS, cpustate->address_size ? REG32(ESI) : REG16(SI) );
}
ead = i386_translate(cpustate, ES, cpustate->address_size ? REG32(EDI) : REG16(DI) );
switch(opcode)
{
@ -1107,7 +1138,7 @@ static void I386OP(repeat)(i386_state *cpustate, int invert_flag)
break;
}
if( cpustate->sreg[CS].d ) {
if( cpustate->address_size ) {
if( REG32(ECX) == 0 )
return;
} else {
@ -1124,7 +1155,7 @@ static void I386OP(repeat)(i386_state *cpustate, int invert_flag)
I386OP(decode_opcode)(cpustate);
CYCLES_NUM(cycle_adjustment);
if (cpustate->sreg[CS].d)
if (cpustate->address_size)
count = --REG32(ECX);
else
count = --REG16(CX);