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sim6800.c
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sim6800.c
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/* M6800 Simulator
* Copyright
* (C) 2011 Joseph H. Allen
*
* This is free software; you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation; either version 1, or (at your option) any later version.
*
* It is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this software; see the file COPYING. If not, write to the Free Software Foundation,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "exor.h"
#include "unasm6800.h"
#include "asm6800.h"
#include "sim6800.h"
int skip = 0; /* Skip first nn instructions in trace */
int trace = 0; /* Enable instruction trace */
int stop; /* Stop flag */
int reset; /* User hit reset */
int abrt; /* User hit abort */
int sp_stop;
/* CPU registers */
unsigned char acca;
unsigned char accb;
unsigned short ix;
unsigned short pc;
unsigned short sp;
unsigned char c_flag;
unsigned char v_flag;
unsigned char z_flag;
unsigned char n_flag;
unsigned char i_flag; /* 1=masked, 0=enabled */
unsigned char h_flag;
/* Breakpoint */
int brk;
unsigned short brk_addr;
/* Trace buffer */
int trace_idx;
#define TRACESIZE 128
struct trace_entry
{
unsigned short ix;
unsigned short pc;
unsigned short sp;
unsigned short ea;
unsigned short data;
unsigned char acca;
unsigned char accb;
unsigned char cc;
unsigned char insn[3];
} trace_buf[TRACESIZE];
unsigned char read_flags()
{
return (0xC0 + c_flag + (v_flag << 1) + (z_flag << 2) + (n_flag << 3) + (i_flag << 4) + (h_flag << 5));
}
void write_flags(unsigned char f)
{
c_flag = (f & 1);
v_flag = ((f >> 1) & 1);
z_flag = ((f >> 2) & 1);
n_flag = ((f >> 3) & 1);
i_flag = ((f >> 4) & 1);
h_flag = ((f >> 5) & 1);
}
unsigned short mread2(unsigned short addr)
{
return (mread(addr) << 8) + mread(addr + 1);
}
unsigned char fetch()
{
unsigned char c = mread(pc++);
return c;
}
unsigned short fetch2()
{
unsigned short v;
v = fetch();
v = (v << 8) + fetch();
return v;
}
void mwrite2(unsigned short addr, unsigned short data)
{
mwrite(addr, (data >> 8));
mwrite(addr + 1, (data & 0xFF));
}
void push(unsigned char data)
{
// printf("push %x\n", data);
mwrite(sp--, data);
}
unsigned char pull()
{
return mread(++sp);
}
void push2(unsigned short data)
{
push(data & 0xFF);
push(data >> 8);
}
unsigned short pull2()
{
unsigned short w;
w = pull();
w = (w << 8) + pull();
return w;
}
#define IDX() (ix + fetch())
#define IMM() ((pc += 1), (pc - 1))
#define IMM2() ((pc += 2), (pc - 2))
#define DIR() (fetch())
#define EXT() (fetch2())
/* Macros which update flags following an arithmetic or logical operation */
#define Z_16(n) ((~((n) | -(n)) >> 15) & 1)
#define Z(n) ((~((n) | -(n)) >> 7) & 1)
#define N_16(n) (n >> 15)
#define N(n) (n >> 7)
#define V_16(a,b,f) ((((f) ^ (a)) & ((f) ^ (b))) >> 15)
#define V(a,b,f) ((((f) ^ (a)) & ((f) ^ (b))) >> 7)
#define C(a,b,f) ((((a) & (b)) | (((a) | (b)) & ~(f))) >> 7)
#define V_SUB(a,b,f) ((((a) ^ (b)) & ((f) ^ (a))) >> 7)
#define C_SUB(a,b,f) (((~(a) & (b)) | ((~(a) | (b)) & (f))) >> 7)
#define H(a,b,f) ((((f) ^ (a) ^ (b)) >> 4) & 1)
/* Print one trace line */
void show_trace(int insn_no, struct trace_entry *t)
{
char *fact_label;
char *fact_comment;
char *ea_label;
char buf_ea[80];
char buf1[80];
char buf[80]; /* Address and fetched data */
char operand[20]; /* Address mode / operand */
char buf3[80]; /* Effective address and data */
char *insn = "Huh?";
int subr = 0;
operand[0] = 0;
buf3[0] = 0;
buf[0] = 0;
/* Any facts about this address? */
fact_label = find_label(t->pc);
fact_comment = "";
if (!fact_label) {
if (facts[t->pc]) {
fact_label = facts[t->pc]->label;
fact_comment = facts[t->pc]->comment;
} else {
fact_label = "";
}
}
/* About the effective address? */
ea_label = find_label(t->ea);
if (!ea_label && facts[t->ea])
ea_label = facts[t->ea]->label;
if (ea_label)
sprintf(buf_ea, "(%s)", ea_label);
else
buf_ea[0] = 0;
if (!(t->cc & 0x40)) {
if (insn_no >= skip) {
fprintf(mon_out, " %10d ---- Subroutine at %4.4X processed by simulator ---- RTS executed ---\n\n",
insn_no, t->pc);
return;
}
}
sprintf(buf,"%4.4X: ", t->pc);
sprintf(buf + strlen(buf), "%2.2X ", t->insn[0]);
if (t->insn[0] & 0x80) {
if ((t->insn[0] & 0x0F) < 0x0C) {
if (t->insn[0] & 0x40) {
sprintf(operand, "B");
} else {
sprintf(operand, "A");
}
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s D=%2.2X", t->ea, buf_ea, t->data);
switch (t->insn[0] & 0x30) {
case 0x00: {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand + strlen(operand), " #%2.2X", t->insn[1]);
break;
} case 0x10: {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand + strlen(operand), " %2.2X", t->insn[1]);
break;
} case 0x20: {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand + strlen(operand), " %2.2X,X", t->insn[1]);
break;
} case 0x30: {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(buf + strlen(buf), "%2.2X ", t->insn[2]);
sprintf(operand + strlen(operand), " %4.4X", (t->insn[1] << 8) + t->insn[2]);
break;
}
}
/* Operate F = A op B */
switch (t->insn[0] & 0x0F) {
case 0x00: /* SUB N,Z,V,C (no H?) */ {
insn = "SUB";
break;
} case 0x01: /* CMP N,Z,V,C (no H?) */ {
insn = "CMP";
break;
} case 0x02: /* SBC N,Z,V,C (no H?) */ {
insn = "SBC";
break;
} case 0x03: /* ??? */ {
goto invalid;
break;
} case 0x04: /* AND N,Z,V=0 */ {
insn = "AND";
break;
} case 0x05: /* BIT N,Z,V=0*/ {
insn = "BIT";
break;
} case 0x06: /* LDA N,Z,V=0 */ {
insn = "LD";
break;
} case 0x07: /* STA N,Z,V=0 */ {
insn = "ST";
break;
} case 0x08: /* EOR N,Z,V=0*/ {
insn = "EOR";
break;
} case 0x09: /* ADC H,N,Z,V,C */ {
insn = "ADC";
break;
} case 0x0A: /* ORA N,Z,V=0 */ {
insn = "OR";
break;
} case 0x0B: /* ADD H,N,Z,V,C */ {
insn = "ADD";
break;
}
}
} else {
/* Compute EA */
switch (t->insn[0] & 0x30) {
case 0x00: {
if (t->insn[0] == 0x8D) {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " $%4.4X", t->pc + (char)t->insn[1]);
} else {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(buf + strlen(buf), "%2.2X ", t->insn[2]);
sprintf(operand, " #$%4.4X", (t->insn[1] << 8) + t->insn[2]);
}
break;
} case 0x10: {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %2.2X", t->insn[1]);
break;
} case 0x20: {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %2.2X,X", t->insn[1]);
break;
} case 0x30: {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(buf + strlen(buf), "%2.2X ", t->insn[2]);
sprintf(operand, " %4.4X", (t->insn[1] << 8) + t->insn[2]);
break;
}
}
switch (t->insn[0]) {
case 0x8C: case 0x9C: case 0xAC: case 0xBC: /* CPX N,Z,V */ {
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s D=%4.4X", t->ea, buf_ea, t->data);
insn = "CPX";
break;
} case 0x8D: /* BSR REL */ {
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
subr = 1;
insn = "BSR";
break;
} case 0x8E: case 0x9E: case 0xAE: case 0xBE: /* LDS N,Z,V */ {
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s D=%4.4X", t->ea, buf_ea, t->data);
insn = "LDS";
break;
} case 0x8F: case 0x9F: case 0xAF: case 0xBF: /* STS N,Z,V */ {
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s D=%4.4X", t->ea, buf_ea, t->data);
insn = "STS";
break;
} case 0xAD: case 0xBD: /* JSR */ {
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "JSR";
subr = 1;
break;
} case 0xCE: case 0xDE: case 0xEE: case 0xFE: /* LDX N,Z,V */ {
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s D=%4.4X", t->ea, buf_ea, t->data);
insn = "LDX";
break;
} case 0xCF: case 0xDF: case 0xEF: case 0xFF: /* STX N,Z,V */ {
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s D=%4.4X", t->ea, buf_ea, t->ix);
insn = "STX";
break;
} default: /* ??? */ {
goto invalid;
break;
}
}
}
} else if (t->insn[0] & 0x40) {
switch (t->insn[0] & 0x30) {
case 0x00: {
sprintf(operand, "A");
break;
} case 0x10: {
sprintf(operand, "B");
break;
} case 0x20: {
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %2.2X,X", t->insn[1]);
break;
} case 0x30: {
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(buf + strlen(buf), "%2.2X ", t->insn[2]);
sprintf(operand, " %4.4X", (t->insn[1] << 8) + t->insn[2]);
break;
}
}
switch (t->insn[0] & 0x0F) {
case 0x00: /* NEG N, Z, V= ((f==0x80)?1:0), C= ((f==0)?1:0) */ {
insn = "NEG";
break;
} case 0x01: /* ??? */ {
goto invalid;
break;
} case 0x02: /* ??? */ {
goto invalid;
break;
} case 0x03: /* COM N, Z, V=0, C=1 */ {
insn = "COM";
break;
} case 0x04: /* LSR N=0,Z,C,V=N^C */ {
insn = "LSR";
break;
} case 0x05: /* ??? */ {
goto invalid;
break;
} case 0x06: /* ROR N,Z,C,V=N^C */ {
insn = "ROR";
break;
} case 0x07: /* ASR N,Z,C,V=N^C */ {
insn = "ASR";
break;
} case 0x08: /* ASL N,Z,C,V=N^C */ {
insn = "ASL";
break;
} case 0x09: /* ROL N,Z,C,V=N^C */ {
insn = "ROL";
break;
} case 0x0A: /* DEC N,Z,V = (a=0x80?1:0) */ {
insn = "DEC";
break;
} case 0x0B: /* ??? */ {
goto invalid;
break;
} case 0x0C: /* INC N,Z,V = (a=0x7F?1:0) */ {
insn = "INC";
break;
} case 0x0D: /* TST N,Z,V=0,C=0 */ {
insn = "TST";
break;
} case 0x0E: /* JMP */ {
insn = "JMP";
break;
} case 0x0F: /* CLR N=0, Z=1, V=0, C=0 */ {
insn = "CLR";
break;
}
}
} else {
switch(t->insn[0]) {
case 0x01: /* NOP */ { /* Do nothing */
insn = "NOP";
break;
} case 0x06: /* TAP (all flags) */ {
insn = "TAP";
break;
} case 0x07: /* TPA */ {
insn = "TPA";
break;
} case 0x08: /* INX Z */ {
insn = "INX";
break;
} case 0x09: /* DEX Z */ {
insn = "DEC";
break;
} case 0x0A: /* CLV */ {
insn = "CLV";
break;
} case 0x0B: /* SEV */ {
insn = "SEV";
break;
} case 0x0C: /* CLC */ {
insn = "CLC";
break;
} case 0x0D: /* SEC */ {
insn = "SEC";
break;
} case 0x0E: /* CLI */ {
insn = "CLI";
break;
} case 0x0F: /* SEI */ {
insn = "SEI";
break;
} case 0x10: /* SBA N,Z,V,C */ {
insn = "SBA";
break;
} case 0x11: /* CBA N,Z,V,C */ {
insn = "CBA";
break;
} case 0x16: /* TAB N,Z,V=0 */ {
insn = "TAB";
break;
} case 0x17: /* TBA N,Z,V=0 */ {
insn = "TBA";
break;
} case 0x19: /* DAA N,Z,V,C */ {
insn = "DAA";
break;
} case 0x1B: /* ABA H,N,Z,V,C */ {
insn = "ABA";
break;
} case 0x20: /* BRA */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BRA";
break;
} case 0x22: /* BHI */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BHI";
break;
} case 0x23: /* BLS */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BLS";
break;
} case 0x24: /* BCC */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BCC";
break;
} case 0x25: /* BCS */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BCS";
break;
} case 0x26: /* BNE */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BNE";
break;
} case 0x27: /* BEQ */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BEQ";
break;
} case 0x28: /* BVC */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BVC";
break;
} case 0x29: /* BVS */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BVS";
break;
} case 0x2A: /* BPL */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BPL";
break;
} case 0x2B: /* BMI */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BMI";
break;
} case 0x2C: /* BGE */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BGE";
break;
} case 0x2D: /* BLT */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BLT";
break;
} case 0x2E: /* BGT */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BGT";
break;
} case 0x2F: /* BLE */ {
sprintf(buf + strlen(buf), "%2.2X ", t->insn[1]);
sprintf(operand, " %4.4X", t->pc + 2 + (char)t->insn[1]);
if (t->cc & 0x80)
sprintf(buf3, "EA=%4.4X%s", t->ea, buf_ea);
insn = "BLE";
break;
} case 0x30: /* TSX */ {
insn = "TSX";
break;
} case 0x31: /* INS */ {
insn = "INS";
break;
} case 0x32: /* PULA */ {
insn = "PULA";
break;
} case 0x33: /* PULB */ {
insn = "PULB";
break;
} case 0x34: /* DES */ {
insn = "DES";
break;
} case 0x35: /* TXS */ {
insn = "TXS";
break;
} case 0x36: /* PSHA */ {
insn = "PSHA";
break;
} case 0x37: /* PSHB */ {
insn = "PSHB";
break;
} case 0x39: /* RTS */ {
insn = "RTS";
subr = 1;
break;
} case 0x3B: /* RTI */ {
insn = "RTI";
subr = 1;
break;
} case 0x3E: /* WAI */ {
insn = "WAI";
break;
} case 0x3F: /* SWI */ {
insn = "SWI";
break;
} default: /* ??? */ {
goto invalid;
break;
}
}
}
invalid:
strcpy(buf1, insn);
strcat(buf1, operand);
if (insn_no >= skip) {
if (pc == t->pc)
fprintf(mon_out, ">");
else
fprintf(mon_out, " ");
fprintf(mon_out, "%10d A=%2.2X B=%2.2X X=%4.4X SP=%4.4X %c%c%c%c%c%c %-8s %-15s%-9s %-14s %s\n",
insn_no, t->acca, t->accb, t->ix, t->sp,
((t->cc & 32) ? 'H' : '-'), ((t->cc & 16) ? 'I' : '-'),
((t->cc & 8) ? 'N' :'-'), ((t->cc & 4) ? 'Z' : '-'),
((t->cc & 2) ? 'V' : '-'), ((t->cc & 1) ? 'C' : '-'), fact_label, buf, buf1, buf3, fact_comment);
if (subr)
fprintf(mon_out, "\n");
}
}
void simulated(unsigned short addr)
{
struct trace_entry *t = trace_buf + (trace_idx++ & (TRACESIZE - 1));
t->cc &= ~0x40;
t->pc = addr;
}
/* Show trace buffer */
void show_traces(int n)
{
int x;
for (x = 0; x != n; ++x) {
show_trace(trace_idx + x - n, trace_buf + ((trace_idx + x - n) & (TRACESIZE - 1)));
}
}
/* This is the simulator */
void sim(void)
{
unsigned char opcode;
for (;;) {
int org_trace_idx = trace_idx;
struct trace_entry *t = (trace_buf + (trace_idx++ & (TRACESIZE - 1)));
int ti = 0;
char offset;
unsigned char imm;
unsigned short ea;
unsigned char a;
unsigned char b;
unsigned char f;
unsigned char data;
unsigned short w;
unsigned short fw;
int wb;
wb = 1;
t->pc = pc;
t->acca = acca;
t->accb = accb;
t->ix = ix;
t->sp = sp;
t->cc = (read_flags() & 0x7F);
t->insn[0] = mread(pc);
t->insn[1] = mread(pc + 1);
t->insn[2] = mread(pc + 2);
t->ea = 0;
t->data = 0;
if (brk && brk_addr == pc || stop) {
if (brk && brk_addr == pc)
printf("\r\nBreakpoint!\n");
monitor();
t->pc = pc;
t->acca = acca;
t->accb = accb;
t->ix = ix;
t->sp = sp;
t->cc = (read_flags() & 0x7F);
t->insn[0] = mread(pc);
t->insn[1] = mread(pc + 1);
t->insn[2] = mread(pc + 2);
t->ea = 0;
t->data = 0;
}
if (reset) {
reset = 0;
abrt = 0;
pc = 0xF000;
if (trace)
printf(" RESET!\n");
t->pc = pc;
t->acca = acca;
t->accb = accb;
t->ix = ix;
t->sp = sp;
t->cc = (read_flags() & 0x7F);
t->insn[0] = mread(pc);
t->insn[1] = mread(pc + 1);
t->insn[2] = mread(pc + 2);
t->ea = 0;
t->data = 0;
}
if (abrt) {
abrt = 0;
push2(pc);
push2(ix);
push(acca);
push(accb);
push(read_flags());
jump(mread2(0xFFFC));
printf(" NMI! to PC=%4.4X\n", pc);
t->pc = pc;
t->acca = acca;
t->accb = accb;
t->ix = ix;
t->sp = sp;
t->cc = (read_flags() & 0x7F);
t->insn[0] = mread(pc);
t->insn[1] = mread(pc + 1);
t->insn[2] = mread(pc + 2);
t->ea = 0;
t->data = 0;
}
opcode = fetch();
if (opcode & 0x80) {
if ((opcode & 0x0F) < 0x0C) {
/* Get operand A */
if (opcode & 0x40) {
a = accb;
} else {
a = acca;
}
/* Get operand B, record effective address */
switch (opcode & 0x30) {
case 0x00: {
ea = IMM();
break;
} case 0x10: {
ea = DIR();
break;
} case 0x20: {
ea = IDX();
break;
} case 0x30: {
ea = EXT();
break;
}
}
if ((opcode & 0x0F) != 0x07) {
b = mread(ea);
t->ea = ea;
t->data = b;
} else {
b = 0;
t->ea = ea;
t->data = a;
}
/* Operate F = A op B */
switch (opcode & 0x0F) {
case 0x00: /* SUB N,Z,V,C (no H?) */ {
f = a - b;
c_flag = C_SUB(a,b,f);
v_flag = V_SUB(a,b,f);
n_flag = N(f);
z_flag = Z(f);
break;
} case 0x01: /* CMP N,Z,V,C (no H?) */ {
f = a - b;
c_flag = C_SUB(a,b,f);
v_flag = V_SUB(a,b,f);
n_flag = N(f);
z_flag = Z(f);
f = a;
break;
} case 0x02: /* SBC N,Z,V,C (no H?) */ {
f = a - b - c_flag;
c_flag = C_SUB(a,b,f);
v_flag = V_SUB(a,b,f);
n_flag = N(f);
z_flag = Z(f);
break;
} case 0x03: /* ??? */ {
goto invalid;
break;
} case 0x04: /* AND N,Z,V=0 */ {
f = (a & b);
n_flag = N(f);
z_flag = Z(f);
v_flag = 0;
break;
} case 0x05: /* BIT N,Z,V=0*/ {
f = (a & b);
n_flag = N(f);
z_flag = Z(f);
v_flag = 0;
f = a;
break;
} case 0x06: /* LDA N,Z,V=0 */ {
f = b;
n_flag = N(f);
z_flag = Z(f);
v_flag = 0;
break;
} case 0x07: /* STA N,Z,V=0 */ {
f = a;
n_flag = N(f);
z_flag = Z(f);
v_flag = 0;
mwrite(ea, f);
break;
} case 0x08: /* EOR N,Z,V=0*/ {
f = a ^ b;
n_flag = N(f);
z_flag = Z(f);
v_flag = 0;
break;
} case 0x09: /* ADC H,N,Z,V,C */ {
f = a + b + c_flag;
v_flag = V(a,b,f);
c_flag = C(a,b,f);
n_flag = N(f);
z_flag = Z(f);
h_flag = H(a,b,f);
break;
} case 0x0A: /* ORA N,Z,V=0 */ {
f = a | b;
n_flag = N(f);
z_flag = Z(f);
v_flag = 0;
break;
} case 0x0B: /* ADD H,N,Z,V,C */ {
f = a + b;
v_flag = V(a,b,f);
c_flag = C(a,b,f);
n_flag = N(f);
z_flag = Z(f);
h_flag = H(a,b,f);
break;
}
}
/* Write back */
if (opcode & 0x40) {
accb = f;
} else {
acca = f;
}
} else {
/* Compute EA */
switch (opcode & 0x30) {
case 0x00: {
ea = IMM2();
break;
} case 0x10: {
ea = DIR();
break;
} case 0x20: {
ea = IDX();
break;
} case 0x30: {
ea = EXT();
break;
}
}
switch (opcode) {
case 0x8C: case 0x9C: case 0xAC: case 0xBC: /* CPX N,Z,V */ {
w = mread2(ea);
t->ea = ea; t->data = w;
fw = ix - w;
z_flag = Z_16(fw);
n_flag = N_16(fw);
v_flag = V_16(ix, w, fw);
break;
} case 0x8D: /* BSR REL */ {
push2(pc - 1);
jump(t->ea = (pc - 1 + (char)mread(ea)));
break;
} case 0x8E: case 0x9E: case 0xAE: case 0xBE: /* LDS N,Z,V */ {
sp = mread2(ea);
t->ea = ea; t->data = sp;
z_flag = Z_16(sp);
n_flag = N_16(sp);
v_flag = 0;
break;
} case 0x8F: case 0x9F: case 0xAF: case 0xBF: /* STS N,Z,V */ {
mwrite2(ea, sp);
t->ea = ea; t->data = sp;
z_flag = Z_16(sp);
n_flag = N_16(sp);
v_flag = 0;
break;
} case 0xAD: case 0xBD: /* JSR */ {
push2(pc);
jump(ea);
t->ea = ea;
break;
} case 0xCE: case 0xDE: case 0xEE: case 0xFE: /* LDX N,Z,V */ {
ix = mread2(ea);
t->ea = ea; t->data = ix;
z_flag = Z_16(ix);
n_flag = N_16(ix);
v_flag = 0;
break;
} case 0xCF: case 0xDF: case 0xEF: case 0xFF: /* STX N,Z,V */ {
mwrite2(ea, ix);
t->ea = ea; t->data = ix;
z_flag = Z_16(ix);
n_flag = N_16(ix);
v_flag = 0;
break;
} default: /* ??? */ {
goto invalid;
break;
}
}
}
} else if (opcode & 0x40) {
switch (opcode & 0x30) {
case 0x00: {
b = acca;
t->data = b;
break;
} case 0x10: {
b = accb;
t->data = b;
break;
} case 0x20: {
ea = IDX();
b = mread(ea);
t->ea = ea; t->data = b;
break;
} case 0x30: {
ea = EXT();
b = mread(ea);
t->ea = ea; t->data = b;
break;
}
}
switch (opcode & 0x0F) {
case 0x00: /* NEG N, Z, V= ((f==0x80)?1:0), C= ((f==0)?1:0) */ {
f = -b;
v_flag = ((b & f) >> 7);
n_flag = N(f);
z_flag = Z(f);
c_flag = z_flag;
break;
} case 0x01: /* ??? */ {
goto invalid;
break;
} case 0x02: /* ??? */ {
goto invalid;
break;
} case 0x03: /* COM N, Z, V=0, C=1 */ {
f = ~b;
c_flag = 1;
n_flag = N(f);
z_flag = Z(f);
v_flag = 0;
break;
} case 0x04: /* LSR N=0,Z,C,V=N^C */ {
f = (b >> 1);
c_flag = (b & 1);
n_flag = 0;
z_flag = Z(f);
v_flag = c_flag;
break;
} case 0x05: /* ??? */ {
goto invalid;
break;
} case 0x06: /* ROR N,Z,C,V=N^C */ {