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asm6800.c
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/* 6800 Assembler
* 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 "asm6800.h"
/* Fixup types */
enum {
FIXUP_EXT, /* An extended address */
FIXUP_DIR, /* An 8-bit address */
FIXUP_REL, /* A branch offset */
};
/* A pending fixup */
struct fixup {
struct fixup *next;
unsigned short fixup; /* Address of data which needs to be fixed up */
int type; /* Type of fixup */
int ofst;
};
/* Symbol table */
struct symbol {
struct symbol *next;
char *name; /* Name of symbol */
int valid; /* Set if symbol's value is known */
unsigned short val; /* Value of symbol */
struct fixup *fixups; /* Fixups waiting for this symbol */
} *symbols;
struct symbol *find_symbol(char *name)
{
struct symbol *sy;
for (sy = symbols; sy; sy = sy->next)
if (!strcmp(sy->name, name))
return sy;
sy = (struct symbol *)malloc(sizeof(struct symbol));
sy->next = symbols;
symbols = sy;
sy->name = strdup(name);
sy->valid = 0;
sy->val = 0;
sy->fixups = 0;
return sy;
}
/* Get symbol name by address */
char *find_label(unsigned short val)
{
struct symbol *sy;
for (sy = symbols; sy; sy = sy->next)
if (sy->val == val)
return sy->name;
return 0;
}
/* Add a fixup */
void add_fixup(struct symbol *sy, unsigned short addr, int type, int ofst)
{
struct fixup *fix = (struct fixup *)malloc(sizeof(struct fixup));
fix->type = type;
fix->fixup = addr;
fix->next = sy->fixups;
fix->ofst = ofst;
sy->fixups = fix;
}
/* Show symbol table */
void show_syms(FILE *f)
{
struct symbol *sy;
for (sy = symbols; sy; sy = sy->next) {
struct fixup *fix;
if (sy->valid) {
fprintf(f,"%4.4X %s\n", sy->val, sy->name);
} else {
fprintf(f,"???? %s\n", sy->name);
}
for (fix = sy->fixups; fix; fix = fix->next) {
if (fix->type == FIXUP_EXT)
fprintf(f," 16-bit fixup at %4.4X\n", fix->fixup);
else if (fix->type == FIXUP_DIR)
fprintf(f," 8-bit fixup at %4.4X\n", fix->fixup);
else if (fix->type == FIXUP_REL)
fprintf(f," 8-bit rel fixup %4.4X\n", fix->fixup);
}
}
}
/* Clear symbol table */
void clr_syms(void)
{
struct symbol *sy;
while (sy = symbols) {
struct fixup *fix;
symbols = sy->next;
while (fix = sy->fixups) {
sy->fixups = fix->next;
free(fix);
}
free(sy->name);
free(sy);
}
}
/* Set symbol's value, process pending fixups */
void set_symbol(unsigned char *mem, struct symbol *sy, unsigned short val)
{
struct fixup *fix;
if (!sy)
return;
if (sy->valid) {
printf("Symbol '%s' already defined to %4.4x\n", sy->name, sy->val);
return;
}
sy->valid = 1;
sy->val = val;
while (fix = sy->fixups) {
sy->fixups = fix->next;
if (fix->type == FIXUP_EXT) {
mem[fix->fixup] = ((val + fix->ofst) >> 8);
mem[fix->fixup + 1] = (val + fix->ofst);
printf("Address at %4.4X set to %4.4X\n", fix->fixup, val + fix->ofst);
} else if (fix->type == FIXUP_DIR) {
mem[fix->fixup] = (val + fix->ofst);
printf("Byte at %4.4X set to %2.2X\n", fix->fixup, ((val + fix->ofst) & 255));
} else if (fix->type == FIXUP_REL) {
mem[fix->fixup] = val + fix->ofst - (fix->fixup + 1);
printf("Offset at %4.4X set to %2.2X\n", fix->fixup, val + fix->ofst - (fix->fixup + 1));
}
free(fix);
}
}
/* Instruction type codes
*
* RM #imm8 -> 0x00
* dir8 -> 0x10
* nn,x -> 0x20
* ext16 -> 0x30
*
* IDX #imm16 -> 0x00
* dir8 -> 0x10
* nn,x -> 0x20
* ext16 -> 0x30
*
* REL rel8
*
* RMW nn,x -> 0x20
* ext16 -> 0x30
*/
enum {
RM, /* Register-Memory */
RMW, /* Read-modify-write */
REL, /* Relative branch */
IDX, /* Index register-Memory */
FCB, /* FCB pseudo-op */
FDB, /* FDB pseudo-op */
EQU, /* EQU pseudo-op */
RMB, /* RMB pseudo-op */
ORG, /* ORG pseudo-op */
IGN, /* Ignore these pseudo-ops */
ACC, /* Accumulator needed */
ACC1, /* Accumulator optional */
ACCB, /* we need an A or a B: add 0x01 for B */
NONE /* No operand */
};
struct { char *insn; int opcode; int type; } table[] =
{
{ "lda", 0x86, ACC1 },
{ "sta", 0x87, ACC1 },
{ "ora", 0x8a, ACC1 },
{ "sub", 0x80, ACC },
{ "cmp", 0x81, ACC },
{ "sbc", 0x82, ACC },
{ "and", 0x84, ACC },
{ "bit", 0x85, ACC },
{ "eor", 0x88, ACC },
{ "adc", 0x89, ACC },
{ "add", 0x8b, ACC },
{ "suba", 0x80, RM },
{ "cmpa", 0x81, RM },
{ "sbca", 0x82, RM },
{ "anda", 0x84, RM },
{ "bita", 0x85, RM },
{ "ldaa", 0x86, RM },
{ "staa", 0x87, RM },
{ "eora", 0x88, RM },
{ "adca", 0x89, RM },
{ "oraa", 0x8a, RM },
{ "adda", 0x8b, RM },
{ "subb", 0xc0, RM },
{ "cmpb", 0xc1, RM },
{ "sbcb", 0xc2, RM },
{ "andb", 0xc4, RM },
{ "bitb", 0xc5, RM },
{ "ldb", 0xc6, RM },
{ "stb", 0xc7, RM },
{ "ldab", 0xc6, RM },
{ "stab", 0xc7, RM },
{ "eorb", 0xc8, RM },
{ "adcb", 0xc9, RM },
{ "orb", 0xca, RM },
{ "orab", 0xca, RM },
{ "addb", 0xcb, RM },
{ "cpx", 0x8c, IDX },
{ "bsr", 0x8d, REL },
{ "lds", 0x8e, IDX },
{ "sts", 0x8f, IDX },
{ "jsr", 0x8d, RMW },
{ "ldx", 0xce, IDX },
{ "stx", 0xcf, IDX },
{ "neg", 0x40, RMW },
{ "com", 0x43, RMW },
{ "lsr", 0x44, RMW },
{ "ror", 0x46, RMW },
{ "asr", 0x47, RMW },
{ "asl", 0x48, RMW },
{ "rol", 0x49, RMW },
{ "dec", 0x4a, RMW },
{ "inc", 0x4c, RMW },
{ "tst", 0x4d, RMW },
{ "jmp", 0x4e, RMW },
{ "clr", 0x4f, RMW },
{ "nega", 0x40, NONE },
{ "coma", 0x43, NONE },
{ "lsra", 0x44, NONE },
{ "rora", 0x46, NONE },
{ "asra", 0x47, NONE },
{ "asla", 0x48, NONE },
{ "rola", 0x49, NONE },
{ "deca", 0x4a, NONE },
{ "inca", 0x4c, NONE },
{ "tsta", 0x4d, NONE },
{ "clra", 0x4f, NONE },
{ "negb", 0x50, NONE },
{ "comb", 0x53, NONE },
{ "lsrb", 0x54, NONE },
{ "rorb", 0x56, NONE },
{ "asrb", 0x57, NONE },
{ "aslb", 0x58, NONE },
{ "rolb", 0x59, NONE },
{ "decb", 0x5a, NONE },
{ "incb", 0x5c, NONE },
{ "tstb", 0x5d, NONE },
{ "clrb", 0x5f, NONE },
{ "nop", 0x01, NONE },
{ "tap", 0x06, NONE },
{ "tpa", 0x07, NONE },
{ "inx", 0x08, NONE },
{ "dex", 0x09, NONE },
{ "clv", 0x0a, NONE },
{ "sev", 0x0b, NONE },
{ "clc", 0x0c, NONE },
{ "sec", 0x0d, NONE },
{ "cli", 0x0e, NONE },
{ "sei", 0x0f, NONE },
{ "sba", 0x10, NONE },
{ "cba", 0x11, NONE },
{ "tab", 0x16, NONE },
{ "tba", 0x17, NONE },
{ "daa", 0x19, NONE },
{ "aba", 0x1b, NONE },
{ "bra", 0x20, REL },
{ "bhi", 0x22, REL },
{ "bls", 0x23, REL },
{ "bcc", 0x24, REL },
{ "bcs", 0x25, REL },
{ "bne", 0x26, REL },
{ "beq", 0x27, REL },
{ "bvc", 0x28, REL },
{ "bvs", 0x29, REL },
{ "bpl", 0x2a, REL },
{ "bmi", 0x2b, REL },
{ "bge", 0x2c, REL },
{ "blt", 0x2d, REL },
{ "bgt", 0x2e, REL },
{ "ble", 0x2f, REL },
{ "tsx", 0x30, NONE },
{ "ins", 0x31, NONE },
{ "pul", 0x32, ACCB },
{ "pula", 0x32, NONE },
{ "pulb", 0x33, NONE },
{ "des", 0x34, NONE },
{ "txs", 0x35, NONE },
{ "psh", 0x36, ACCB },
{ "psha", 0x36, NONE },
{ "pshb", 0x37, NONE },
{ "rts", 0x39, NONE },
{ "rti", 0x3b, NONE },
{ "wai", 0x3e, NONE },
{ "swi", 0x3f, NONE },
{ "fcb", 0, FCB },
{ "fcc", 0, FCB },
{ "fdb", 0, FDB },
{ "equ", 0, EQU },
{ "rmb", 0, RMB },
{ "org", 0, ORG },
{ "end", 0, IGN },
{ "mon", 0, IGN },
{ "opt", 0, IGN },
{ "nam", 0, IGN },
{ "ttl", 0, IGN },
{ "spc", 0, IGN },
{ "page", 0, IGN },
{ 0, 0, 0 }
};
/* Parse a value (this should really be an expression parser) */
int parse_val(char **buf, int *operand, struct symbol **sy, unsigned short addr)
{
char str[80];
*sy = 0;
if (!parse_dec(buf, operand)) {
if (parse_word(buf, str)) {
char *p;
if (!strcmp(str, "*")) {
*operand = addr;
} else {
*sy = find_symbol(str);
*operand = (*sy)->val;
if ((*sy)->valid)
*sy = 0;
}
p = *buf;
if (*p == '+' || *p == '-') {
char c = *p++;
int ofst;
*buf = p;
if (parse_dec(buf, &ofst)) {
if (c == '+')
*operand += ofst;
else
*operand -= ofst;
} else {
printf("Missing value after + or -\n");
}
}
} else {
return 0;
}
}
return 1;
}
unsigned assemble(unsigned char *mem, unsigned addr, char *buf)
{
char str[80];
unsigned short label_addr = addr;
struct symbol *label_sy;
struct symbol *sy;
int opcode = -1;
int operand;
int type;
char *p;
int c;
int x;
label_sy = 0;
sy = 0;
if (buf[0] == '*' || !buf[0]) {
/* Comment line, ignore */
return addr;
}
if (!(buf[0] == ' ' || buf[0] == '\t') && parse_word(&buf, str)) {
/* A label */
label_sy = find_symbol(str);
skipws(&buf);
if (!parse_word(&buf, str)) {
goto done;
}
} else {
skipws(&buf);
if (!parse_word(&buf, str)) {
printf("Huh?\n");
return addr;
}
}
/* Lookup instruction */
for (x = 0; table[x].insn; ++x)
if (!jstricmp(table[x].insn, str)) {
opcode = table[x].opcode;
type = table[x].type;
break;
}
if (!table[x].insn) {
printf("Huh?\n");
return addr;
}
skipws(&buf);
if (type == IGN) {
goto done;
} else if (type == NONE) {
mem[addr++] = opcode;
goto done;
} else if (type == ACC) {
type = RM;
if ((buf[0] == 'a' || buf[0] == 'A') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
buf++;
} else if ((buf[0] == 'b' || buf[0] == 'B') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
opcode += 0x40;
buf++;
} else {
printf("Accu missing after intrustion\n");
return addr;
}
skipws(&buf);
goto norm;
} else if (type == ACC1) {
type = RM;
if ((buf[0] == 'a' || buf[0] == 'A') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
buf++;
} else if ((buf[0] == 'b' || buf[0] == 'B') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
opcode += 0x40;
buf++;
}
skipws(&buf);
goto norm;
} else if (type == RMW) {
/* More syntax of old asm: psh a, inc a, etc. */
if ((buf[0] == 'a' || buf[0] == 'A') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
mem[addr++] = opcode;
goto done;
} else if ((buf[0] == 'b' || buf[0] == 'B') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
mem[addr++] = opcode + 0x10;
goto done;
} else {
goto normal;
}
} else if (type == ACCB) {
/* More syntax of old asm: psh a, inc a, etc. */
if ((buf[0] == 'a' || buf[0] == 'A') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
mem[addr++] = opcode;
goto done;
} else if ((buf[0] == 'b' || buf[0] == 'B') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
mem[addr++] = opcode + 0x01;
goto done;
} else {
printf("Missing accumulator\n");
return addr;
}
} else if (type == FCB) {
char c;
if (!*buf) {
printf("Missing value\n");
return addr;
}
fcb_loop:
/* Special case for FCB/FCC */
if (*buf == '"' || *buf == '/') {
c = *buf++;
while (*buf && *buf != c) {
mem[addr++] = *buf++;
}
if (*buf)
++buf;
} else if (parse_val(&buf, &operand, &sy, addr)) {
if (sy) {
add_fixup(sy, addr, FIXUP_DIR, operand);
mem[addr++] = 0;
} else {
mem[addr++] = operand;
}
} else {
mem[addr++] = 0;
}
skipws(&buf);
if (buf[0] == ',') {
++buf;
skipws(&buf);
goto fcb_loop;
}
goto done;
} else {
norm:
if (*buf == '#') {
++buf;
if (!parse_val(&buf, &operand, &sy, addr)) {
printf("Missing number or label after #\n");
return addr;
}
if (type == RM) {
/* 8-bit immediate */
mem[addr++] = opcode;
if (sy)
add_fixup(sy, addr, FIXUP_DIR, operand);
mem[addr++] = operand;
goto done;
} else if (type == IDX) {
/* 16-bit immediate */
mem[addr++] = opcode;
if (sy)
add_fixup(sy, addr, FIXUP_EXT, operand);
mem[addr++] = (operand >> 8);
mem[addr++] = operand;
goto done;
} else {
printf("Invalid operand\n");
return addr;
}
} else {
normal:
/* Check for stupid syntax of old asm: lda x is same as lda 0,x */
if ((buf[0] == 'x' || buf[0] == 'X') && (!buf[1] || buf[1] == ' ' || buf[1] == '\t')) {
operand = 0;
goto ndx;
}
if (parse_val(&buf, &operand, &sy, addr)) {
if (buf[0] == ',' && (buf[1] == 'x' || buf[1] == 'X')) {
ndx:
/* We have an indexed operand */
if (type == RM || type == IDX || type == RMW) {
mem[addr++] = opcode + 0x20;;
if (sy)
add_fixup(sy, addr, FIXUP_DIR, operand);
mem[addr++] = operand;
goto done;
} else {
printf("Invalid operand for this instruction\n");
return addr;
}
} else {
/* We have a direct address operand */
if ((type == RM || type == IDX) && !sy && operand < 256) {
mem[addr++] = opcode + 0x10;
mem[addr++] = operand;
goto done;
} else if (type == RM || type == IDX || type == RMW) {
mem[addr++] = opcode + 0x30;
if (sy)
add_fixup(sy, addr, FIXUP_EXT, operand);
mem[addr++] = (operand >> 8);
mem[addr++] = operand;
goto done;
} else if (type == REL) {
mem[addr++] = opcode;
if (sy) {
mem[addr] = 0;
add_fixup(sy, addr, FIXUP_REL, operand);
} else {
mem[addr] = operand - (addr + 1);
}
addr++;
goto done;
} else if (type == FDB) {
if (!*buf) {
printf("Value missing\n");
return addr;
}
more_fdb:
if (sy) {
add_fixup(sy, addr, FIXUP_EXT, operand);
mem[addr++] = 0;
mem[addr++] = 0;
} else {
mem[addr++] = (operand >> 8);
mem[addr++] = operand;
}
skipws(&buf);
if (buf[0] == ',') {
++buf;
skipws(&buf);
if (parse_val(&buf, &operand, &sy, addr)) {
goto more_fdb;
} else {
operand = 0;
sy = 0;
goto more_fdb;
}
}
goto done;
} else if (type == RMB) {
if (sy) {
printf("Resolved symbol required for rmb\n");
} else {
addr += operand;
}
goto done;
} else if (type == EQU) {
if (sy) {
printf("Resolved symbol required for equ\n");
} else if (!label_sy) {
printf("Label required for equ\n");
} else {
label_addr = operand;
}
goto done;
} else if (type == ORG) {
if (sy) {
printf("Resolved symbol required for org\n");
}
label_addr = addr = operand;
goto done;
} else {
printf("Invalid operand for this instruction\n");
return addr;
}
}
}
/* We have no operand */
if (type == NONE) {
mem[addr++] = opcode;
goto done;
} else {
printf("Operand required\n");
return addr;
}
}
}
done:
set_symbol(mem, label_sy, label_addr);
return addr;
}