6502/65816.js
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added XBA

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Preston Skupinski 2011-05-13 13:51:10 -04:00
parent 0fd6d30fe3
commit e2341a63a1
1 changed files with 32 additions and 1 deletions
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33
cpu.js
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@ -46,7 +46,7 @@ function CPU_65816() {
this.opcode_map = { 0xfb : XCE, 0x18 : CLC, 0x78 : SEI, 0x38 : SEC,
0x58 : CLI, 0xc2 : REP, 0xe2 : SEP, 0xd8 : CLD,
0xf8 : SED, 0xb8 : CLV, 0xa9 : LDA_const,
0xf8 : SED, 0xb8 : CLV, 0xeb : XBA, 0xa9 : LDA_const,
0xad : LDA_absolute, 0xaf : LDA_absolute_long,
0xa5 : LDA_direct_page, 0xbd : LDA_absolute_indexed_x,
0xb9 : LDA_absolute_indexed_y,
@ -3625,3 +3625,34 @@ var CLV = {
cpu.p.v = 0;
}
};
var XBA = {
bytes_required:function() {
return 1;
},
execute:function(cpu) {
if(cpu.p.e|cpu.p.m) {
var old_a = cpu.r.a;
cpu.r.a = cpu.r.b;
cpu.r.b = old_a;
cpu.p.n = cpu.r.a >> 7;
if(cpu.r.a===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
} else {
var low_byte = cpu.r.a & 0xff;
var high_byte = cpu.r.a >> 8;
cpu.r.a = (low_byte<<8)|high_byte;
cpu.p.n = high_byte >> 7;
if(high_byte===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
}
};