6502/65816.js
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added STA and LDA absolute long

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Preston Skupinski 2011-05-01 20:09:14 -04:00
parent 09fce7cff5
commit 4828d9c1b1
1 changed files with 50 additions and 0 deletions
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cpu.js
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@ -47,6 +47,7 @@ function CPU_65816() {
this.opcode_map = { 0xfb : XCE, 0x18 : CLC, 0x78 : SEI, 0x38 : SEC,
0x58 : CLI, 0xc2 : REP, 0xe2 : SEP,
0xa9 : LDA_const, 0xad : LDA_absolute,
0xaf : LDA_absolute_long,
0xa5 : LDA_direct_page, 0xbd : LDA_absolute_indexed_x,
0xb9 : LDA_absolute_indexed_y,
0xb2 : LDA_direct_page_indirect,
@ -58,6 +59,7 @@ function CPU_65816() {
0xb6 : LDX_direct_page_indexed_y,
0xac : LDY_absolute, 0xa4 : LDY_direct_page, 0xea : NOP,
0x8d : STA_absolute, 0x85 : STA_direct_page,
0x8f : STA_absolute_long,
0x92 : STA_direct_page_indirect,
0x9d : STA_absolute_indexed_x,
0x99 : STA_absolute_indexed_y,
@ -83,10 +85,21 @@ var MMU = {
return this.memory[cpu.r.dbr][location];
},
read_byte_long: function(location, bank) {
return this.memory[bank][location];
},
store_byte: function(location, b) {
this.memory[cpu.r.dbr][location] = b;
},
store_byte_long: function(location, bank, b) {
if(typeof this.memory[bank] === 'undefined') {
this.memory[bank] = {};
}
this.memory[bank][location] = b;
},
load_rom: function(raw_hex) {
var loc = 0x8000;
byte_buffer = [];
@ -841,6 +854,23 @@ var STX_absolute = {
}
};
var STA_absolute_long = {
bytes_required: function() {
return 4;
},
execute: function(cpu, bytes) {
var location = (bytes[1]<<8)|bytes[0];
if(cpu.p.m===1) {
cpu.mmu.store_byte_long(location, bytes[2], cpu.r.a);
} else {
var high_byte = cpu.r.a & 0xFF00;
var low_byte = cpu.r.a & 0x00FF;
cpu.mmu.store_byte_long(location, bytes[2], low_byte);
cpu.mmu.store_byte_long(location+1, bytes[2], high_byte);
}
}
};
var STA_absolute = {
bytes_required: function() {
return 3;
@ -970,6 +1000,26 @@ var LDX_absolute = {
}
};
var LDA_absolute_long = {
bytes_required: function() {
return 4;
},
execute: function(cpu, bytes) {
var location = (bytes[1]<<8)|bytes[0];
if(cpu.p.m===1) {
cpu.r.a = cpu.mmu.read_byte_long(location, bytes[2]);
} else {
var low_byte = cpu.mmu.read_byte_long(location, bytes[2]);
var high_byte = cpu.mmu.read_byte_long(location+1, bytes[2]);
cpu.r.a = high_byte | low_byte;
}
if(cpu.r.a===0) {
cpu.p.z = 1;
}
// TODO: Set the n status bit of the p status register.
}
};
var LDA_absolute = {
bytes_required: function() {
return 3;