6502
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65816.js
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added DEC and INC direct page indexed x and absolute indexed x

This commit is contained in:
Preston Skupinski 2011-05-23 21:37:28 -04:00
parent 4998c9c4dc
commit 688c2aaaa3
2 changed files with 174 additions and 6 deletions
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4
TODO
View File

@ -23,13 +23,9 @@ Operations Not Yet Implemented:
- 0x9a : TXS
- 0xba : TSX
- 0xcb : WAI
- 0xd6 : DEC direct page indexed x
- 0xdb : STP
- 0xdc : JMP absolute indirect long
- 0xde : DEC absolute indexed x
- 0xf6 : INC direct page indexed x
- 0xfc : JSR absolute indexed x indirect
- 0xfe : INC absolute indexed x
CPU:
- More work on interrupts
- Decimal mode support

176
cpu.js
View File

@ -87,9 +87,13 @@ function CPU_65816() {
0x8c : STY_absolute, 0x84 : STY_direct_page,
0x94 : STY_direct_page_indexed_x,
0x1a : INC_accumulator, 0xe6 : INC_direct_page,
0xee : INC_absolute, 0xe8 : INX, 0xc8 : INY,
0xee : INC_absolute, 0xf6 : INC_direct_page_indexed_x,
0xfe : INC_absolute_indexed_x,
0xe8 : INX, 0xc8 : INY,
0x3a : DEC_accumulator, 0xce : DEC_absolute,
0xde : DEC_absolute_indexed_x,
0xc6 : DEC_direct_page, 0xca : DEX, 0x88 : DEY,
0xd6 : DEC_direct_page_indexed_x,
0x9c : STZ_absolute, 0x64 : STZ_direct_page,
0x9e : STZ_absolute_indexed_x,
0x74 : STZ_direct_page_indexed_x, 0x9b : TXY,
@ -4748,7 +4752,7 @@ var DEC_absolute = {
return 3;
},
execute: function(cpu, bytes) {
var location = (bytes[1]<<8)|bytes[0]
var location = (bytes[1]<<8)|bytes[0];
var temp;
if(cpu.p.e|cpu.p.m) {
temp = cpu.mmu.read_byte(location);
@ -4791,6 +4795,54 @@ var DEC_absolute = {
}
};
var DEC_absolute_indexed_x = {
bytes_required: function() {
return 3;
},
execute: function(cpu, bytes) {
var location = ((bytes[1]<<8)|bytes[0]) + cpu.r.x;
var temp;
if(cpu.p.e|cpu.p.m) {
temp = cpu.mmu.read_byte(location&0xffff);
if(temp===0) {
cpu.mmu.store_byte(location&0xffff, 0xff);
cpu.p.n = 1;
cpu.p.z = 0;
} else {
temp--;
cpu.mmu.store_byte(location&0xffff, temp);
cpu.p.n = temp >> 7;
if(temp===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
} else {
var low_byte = cpu.mmu.read_byte(location&0xffff);
var high_byte = cpu.mmu.read_byte((location+1)&0xffff);
temp = (high_byte<<8) | low_byte;
if(temp===0) {
temp = 0xffff;
cpu.p.n = 1;
cpu.p.z = 0;
} else {
temp--;
cpu.p.n = temp >> 15;
if(temp===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
high_byte = temp >> 8;
low_byte = temp & 0x00ff;
cpu.mmu.store_byte(location&0xffff, low_byte);
cpu.mmu.store_byte((location+1)&0xffff, high_byte);
}
}
};
var DEC_direct_page = {
bytes_required: function() {
return 2;
@ -4839,6 +4891,54 @@ var DEC_direct_page = {
}
};
var DEC_direct_page_indexed_x = {
bytes_required: function() {
return 2;
},
execute: function(cpu, bytes) {
var location = bytes[0] + cpu.r.d + cpu.r.x;
var temp;
if(cpu.p.e|cpu.p.m) {
temp = cpu.mmu.read_byte(location&0xffff);
if(temp===0) {
cpu.mmu.store_byte(location&0xffff, 0xff);
cpu.p.n = 1;
cpu.p.z = 0;
} else {
temp--;
cpu.mmu.store_byte(location&0xffff, temp);
cpu.p.n = temp >> 7;
if(temp===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
} else {
var low_byte = cpu.mmu.read_byte(location&0xffff);
var high_byte = cpu.mmu.read_byte((location+1)&0xffff);
temp = (high_byte<<8) | low_byte;
if(temp===0) {
temp = 0xffff;
cpu.p.n = 1;
cpu.p.z = 0;
} else {
temp--;
cpu.p.n = temp >> 15;
if(temp===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
high_byte = temp >> 8;
low_byte = temp & 0x00ff;
cpu.mmu.store_byte(location&0xffff, low_byte);
cpu.mmu.store_byte((location+1)&0xffff, high_byte);
}
}
};
var INX = {
bytes_required:function() {
return 1;
@ -4942,6 +5042,42 @@ var INC_absolute = {
}
};
var INC_absolute_indexed_x = {
bytes_required: function() {
return 3;
},
execute: function(cpu, bytes) {
var location = ((bytes[1]<<8)|bytes[0]) + cpu.r.x;
var temp;
if(cpu.p.e|cpu.p.m) {
temp = cpu.mmu.read_byte(location&0xffff) + 1;
temp &= 0xff;
cpu.p.n = temp >> 7;
cpu.mmu.store_byte(location&0xffff, temp);
if(temp===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
} else {
var low_byte = cpu.mmu.read_byte(location&0xffff);
var high_byte = cpu.mmu.read_byte((location+1)&0xffff);
temp = (high_byte<<8) | low_byte;
temp++;
cpu.p.n = temp >> 15;
high_byte = temp >> 8;
low_byte = temp & 0x00ff;
cpu.mmu.store_byte(location&0xffff, low_byte);
cpu.mmu.store_byte((location+1)&0xffff, high_byte);
if(((high_byte<<8)|low_byte)===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
}
};
var INC_direct_page = {
bytes_required: function() {
return 2;
@ -4978,6 +5114,42 @@ var INC_direct_page = {
}
};
var INC_direct_page_indexed_x = {
bytes_required: function() {
return 2;
},
execute: function(cpu, bytes) {
var location = bytes[0] + cpu.r.d + cpu.r.x;
var temp;
if(cpu.p.e|cpu.p.m) {
temp = cpu.mmu.read_byte(location&0xffff) + 1;
temp &= 0xff;
cpu.mmu.store_byte(location&0xffff, temp);
cpu.p.n = temp >> 7;
if(temp===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
} else {
var low_byte = cpu.mmu.read_byte(location&0xffff);
var high_byte = cpu.mmu.read_byte((location+1)&0xffff);
temp = (high_byte<<8) | low_byte;
temp++;
cpu.p.n = temp >> 15;
high_byte = temp >> 8;
low_byte = temp & 0x00ff;
cpu.mmu.store_byte(location&0xffff, low_byte);
cpu.mmu.store_byte((location+1)&0xffff, high_byte);
if(((high_byte<<8)|low_byte)===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
}
};
var STA_direct_page_indexed_x = {
bytes_required: function() {
return 2;