6502/65816.js
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added EOR and many addressing modes for it

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Preston Skupinski 2011-05-08 01:11:11 -04:00
parent 8e3363b1e8
commit c941641d6a
1 changed files with 116 additions and 1 deletions
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117
cpu.js
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@ -104,7 +104,13 @@ function CPU_65816() {
0x12 : ORA_direct_page_indirect,
0x1d : ORA_absolute_indexed_x,
0x1f : ORA_absolute_indexed_y,
0x15 : ORA_direct_page_indexed_x };
0x15 : ORA_direct_page_indexed_x,
0x49 : EOR_const, 0x4d : EOR_absolute,
0x45 : EOR_direct_page,
0x52 : EOR_direct_page_indirect,
0x5d : EOR_absolute_indexed_x,
0x59 : EOR_absolute_indexed_y,
0x55 : EOR_direct_page_indexed_x };
/**
* Take a raw hex string representing the program and execute it.
@ -183,6 +189,115 @@ var MMU = {
}
};
var EOR_const = {
bytes_required:function(cpu) {
if(cpu.p.m) {
return 2;
} else {
return 3;
}
},
execute:function(cpu, bytes) {
if(cpu.p.m) {
cpu.r.a ^= bytes[0];
cpu.p.n = cpu.r.a >> 7;
} else {
cpu.r.a ^= (bytes[1]<<8)|bytes[0];
cpu.p.n = cpu.r.a >> 15;
}
if(cpu.r.a===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
};
var EOR_absolute = {
bytes_required:function() {
return 3;
},
execute:function(cpu, bytes) {
var location = (bytes[1]<<8)|bytes[0];
if(cpu.p.m) {
EOR_const.execute(cpu, [cpu.mmu.read_byte(location)]);
} else {
var low_byte = cpu.mmu.read_byte(location);
var high_byte = cpu.mmu.read_byte(location+1);
EOR_const.execute(cpu, [low_byte, high_byte]);
}
}
};
var EOR_direct_page = {
bytes_required:function() {
return 2;
},
execute:function(cpu, bytes) {
var location = bytes[0] + cpu.r.d;
if(cpu.p.m) {
EOR_const.execute(cpu, cpu.mmu.read_byte(location));
} else {
var low_byte = cpu.mmu.read_byte(location);
var high_byte = cpu.mmu.read_byte(location+1);
EOR_const.execute(cpu, [low_byte, high_byte]);
}
}
};
var EOR_direct_page_indirect = {
bytes_required:function() {
return 2;
},
execute:function(cpu, bytes) {
var location = bytes[0] + cpu.r.d;
var low_byte_loc = cpu.mmu.read_byte(location);
var high_byte_loc = cpu.mmu.read_byte(location+1);
var absolute_location = (high_byte_loc<<8) | low_byte_loc;
if(cpu.p.m) {
EOR_const.execute(cpu, [cpu.mmu.read_byte(absolute_location)]);
} else {
var low_byte = cpu.mmu.read_byte(absolute_location);
var high_byte = cpu.mmu.read_byte(absolute_location+1);
EOR_const.execute(cpu, [low_byte, high_byte]);
}
}
};
var EOR_absolute_indexed_x = {
bytes_required:function() {
return 3;
},
execute:function(cpu, bytes) {
var location = ((bytes[1]<<8)|bytes[0])+cpu.r.x;
var location_high_byte = (location & 0xff00)>>8;
var location_low_byte = location & 0x00ff;
EOR_absolute.execute(cpu, [location_low_byte, location_high_byte]);
}
};
var EOR_absolute_indexed_y = {
bytes_required:function() {
return 3;
},
execute:function(cpu, bytes) {
var location = ((bytes[1]<<8)|bytes[0])+cpu.r.y;
var location_high_byte = (location & 0xff00)>>8;
var location_low_byte = location & 0x00ff;
EOR_absolute.execute(cpu, [location_low_byte, location_high_byte]);
}
};
var EOR_direct_page_indexed_x = {
bytes_required:function() {
return 2;
},
execute:function(cpu, bytes) {
EOR_direct_page.execute(cpu, [bytes[0]+cpu.r.x]);
}
};
var ORA_const = {
bytes_required:function(cpu) {
if(cpu.p.m) {