cpu/disasm: SBC insn, readme: update

cpu.c

@@ -29,6 +29,12 @@ uint8_t cpu_adc(cpu_t*cpu,uint8_t x)
 	return cpu->a+=x;
 }
 
+// Increment cpu->a by x (for sequence point)
+uint8_t cpu_sbc(cpu_t*cpu,uint8_t x)
+{
+	return cpu->a-=x;
+}
+
 // Assign x to cpu->a (for sequence point)
 uint8_t cpu_assign(cpu_t*cpu,uint8_t x)
 {
@@ -112,6 +118,17 @@ void cpu_exec(cpu_t*cpu,ram_t*ram)
 		case 0x61: adc( deref( fetch() + cpu->x ) );			sr_nz(cpu->a);	incpc();	break;
 		case 0x71: adc( deref( fetch() + cpu->y ) );			sr_nz(cpu->a);	incpc();	break;
 
+		// SBC
+		case 0xE5: sbc( deref( fetch() ) );				sr_nz(cpu->a); incpc(); break;
+		case 0xE9: sbc( fetch() );						sr_nz(cpu->a); incpc(); break;
+		case 0xF5: sbc( deref( fetch() + cpu->x ) );	sr_nz(cpu->a); incpc(); break;
+		case 0xED: sbc( deref( fetch16() ) );			sr_nz(cpu->a); incpc(); break;
+		case 0xFD: sbc( deref( fetch16() + cpu->x ) );	sr_nz(cpu->a); incpc(); break;
+		case 0xF9: sbc( deref( fetch16() + cpu->y ) );	sr_nz(cpu->a); incpc(); break;
+		// TODO Verify these are correct
+		case 0xE1: sbc( deref( deref( fetch() + cpu->x ) ) );	sr_nz(cpu->a); incpc(); break;
+		case 0xF1: sbc( deref( deref( fetch() + cpu->y ) ) );	sr_nz(cpu->a); incpc(); break;
+
 		// INC/DEC
 		case 0xE6: ram->ram[ fetch() ] += 1;	incpc();	break;
 		case 0xF6: ram->ram[ fetch() + cpu->x ] += 1;	incpc();	break;

cpu.h

@@ -74,6 +74,7 @@ typedef struct cpu_t
 
 // Arithmetic micro-insns
 #define adc(x)		(cpu_adc(__cpu,x))
+#define sbc(x)		(cpu_sbc(__cpu,x))
 // TODO AND is not always for accumulator
 #define and(x)		(__cpu->a &= (x))
 #define eor(x)		(__cpu->a ^= (x))
@@ -101,5 +102,6 @@ cpu_t*cpu_init(void);
 void cpu_exec(cpu_t*cpu,ram_t*ram);
 uint16_t cpu_fetch(cpu_t*cpu);
 uint8_t cpu_adc(cpu_t*cpu,uint8_t x);
+uint8_t cpu_sbc(cpu_t*cpu,uint8_t x);
 uint8_t cpu_assign(cpu_t*cpu,uint8_t x);
 void cpu_push(cpu_t*cpu,ram_t*ram,uint8_t b);

disasm.c

@@ -135,6 +135,7 @@ void da_print_disassembly(cpu_t*cpu,ram_t*ram)
 		case 0x98: p1( "tya" ); end();
 
 		// Arithmetic
+		// ADC
 		case 0x65: p2( "adc zp $%02X", imm_pk(1) ); end();
 		case 0x69: p2( "adc #$%02X", imm_pk(1) ); end();
 		case 0x75: p2( "adc zp $%02X,x", imm_pk(1) ); end();
@@ -145,6 +146,16 @@ void da_print_disassembly(cpu_t*cpu,ram_t*ram)
 		case 0x61: p2( "adc ind ($%02X,x)", imm_pk(1) ); end();
 		case 0x71: p2( "adc ind ($%02X),y", imm_pk(1) ); end();
 
+		// SBC
+		case 0xE5: p2( "sbc zp $%02X", imm_pk(1) ); end();
+		case 0xE9: p2( "sbc #$%02X", imm_pk(1) ); end();
+		case 0xF5: p2( "sbc zp $%02X,x", imm_pk(1) ); end();
+		case 0xED: p3( "sbc abs $%04X", imm16_pk(1) ); end();
+		case 0xFD: p3( "sbc abs $%04X,x", imm16_pk(1) ); end();
+		case 0xF9: p3( "sbc abs $%04X,y", imm16_pk(1) ); end();
+		case 0xE1: p2( "sbc ind ($%02X,x)", imm_pk(1) ); end();
+		case 0xF1: p2( "sbc ind ($%02X),y", imm_pk(1) ); end();
+
 		// INC/DEC
 		case 0xE6: p2( "inc zp $%02X", imm_pk(1) ); end();
 		case 0xF6: p2( "inc zp $%02X,x", imm_pk(1) ); end();

disasm.h

@@ -1,6 +1,6 @@
 #pragma once
 #include<ncurses.h>
-#include<yaml.h>
+//#include<yaml.h>
 #include<stdio.h>
 #include<stdlib.h>
 #include<string.h>
@@ -22,7 +22,7 @@
 		//   bytes: 1
 		//   ...
 
-yaml_parser_t parser;
-yaml_event_t event;
+//yaml_parser_t parser;
+//yaml_event_t event;
 
 void da_print_disassembly(cpu_t*cpu,ram_t*ram);

readme.md

@@ -8,7 +8,21 @@ A 6502 CPU emulator/simulator with ncurses UI.
 
 #### Usage
 
-`65 FILE.NES`
+`./65 FILE.NES`
+
+#### Building
+
+Dependencies:
+
+ncurses / pdcurses (on Windows)
+
+To build using GNUMake:
+
+	make
+
+To build using Ruby rake
+
+	rake
 
 #### Key bindings:
 
@@ -23,5 +37,7 @@ j.........Scroll down through hexdump
 
 k.........Scroll up through hexdump
 
+/.........Search for octet
+
 q.........Quit program
 ```

test/nes.a65

@@ -7,15 +7,22 @@ reg=$0102
 *=$8000
 main:
 
-	lda #$01
-	tay
+	ldx #$00
 
-	ldy #$55
-	tya
+	lda #$00
+	sta $05,x
 
-	ldx #$44
-	txs
-	txa
+	inx
+
+	lda #$10
+	sta $05,x
+
+	lda #$55
+	sta $0100
+
+	lda #$99
+	ldx #$00
+	sbc ($05,x)
 
 	jsr main