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65816.js
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added TAX, TAY, TXA and TYA

This commit is contained in:
Preston Skupinski 2011-05-01 13:15:16 -04:00
parent 08593831b3
commit b167d4c164
1 changed files with 97 additions and 1 deletions
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98
cpu.js
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@ -68,7 +68,8 @@ function CPU_65816() {
0x9c : STZ_absolute, 0x64 : STZ_direct_page,
0x9e : STZ_absolute_indexed_x,
0x74 : STZ_direct_page_indexed_x, 0x9b : TXY,
0xbb : TYX };
0xbb : TYX, 0xaa : TAX, 0xa8 : TAY, 0x8a : TXA,
0x98 : TYA };
}
var MMU = {
@ -97,6 +98,101 @@ var MMU = {
}
};
var TYA = {
bytes_required:function() {
return 1;
},
execute:function(cpu) {
if(cpu.p.m===1) {
if(cpu.p.x===1) {
// 8-bit index register to 8-bit accumulator.
cpu.r.a = cpu.r.y;
} else {
// 16-bit index register to 8-bit accumulator.
cpu.r.a = cpu.r.y & 0x00ff;
}
} else {
// 8-bit index register to 16-bit accumulator.
// 16-bit index register to 16-bit accumulator.
cpu.r.a = cpu.r.y;
}
}
};
var TAY = {
bytes_required:function() {
return 1;
},
execute:function(cpu) {
if(cpu.p.m==1) {
if(cpu.p.x==1) {
// 8-bit accumulator to 8-bit x index register.
cpu.r.y = cpu.r.a;
} else {
// 8-bit accumulator to 16-bit x index register.
cpu.r.y = cpu.r.b; // Transfer b as high-byte of x.
cpu.r.y |= cpu.r.a; // Use the bitwise or to add a as the low-byte.
}
} else {
if(cpu.p.x==1) {
// 16-bit accumulator to 8-bit x index register.
cpu.r.y = cpu.r.a & 0x00ff; // Transfer only the low-byte to x.
} else {
// 16-bit accumulator to 16-bit x index register.
cpu.r.y = cpu.r.a;
}
}
}
};
var TXA = {
bytes_required:function() {
return 1;
},
execute:function(cpu) {
if(cpu.p.m===1) {
if(cpu.p.x===1) {
// 8-bit index register to 8-bit accumulator.
cpu.r.a = cpu.r.x;
} else {
// 16-bit index register to 8-bit accumulator.
cpu.r.a = cpu.r.x & 0x00ff;
}
} else {
// 8-bit index register to 16-bit accumulator.
// 16-bit index register to 16-bit accumulator.
cpu.r.a = cpu.r.x;
}
}
};
var TAX = {
bytes_required:function() {
return 1;
},
execute:function(cpu) {
if(cpu.p.m==1) {
if(cpu.p.x==1) {
// 8-bit accumulator to 8-bit x index register.
cpu.r.x = cpu.r.a;
} else {
// 8-bit accumulator to 16-bit x index register.
cpu.r.x = cpu.r.b; // Transfer b as high-byte of x.
cpu.r.x |= cpu.r.a; // Use the bitwise or to add a as the low-byte.
}
} else {
if(cpu.p.x==1) {
// 16-bit accumulator to 8-bit x index register.
cpu.r.x = cpu.r.a & 0x00ff; // Transfer only the low-byte to x.
} else {
// 16-bit accumulator to 16-bit x index register.
cpu.r.x = cpu.r.a;
}
}
}
};
var TXY = {
bytes_required:function() {
return 1;