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assemble.c
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assemble.c
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/* Definition file for the module that takes care of the assembly */
#include <string.h>
#include "as6502.h"
#include "assemble.h"
#include "code.h"
#include "id.h"
#include "jos.h"
#include "utils.h"
#define NR_OF_MNEMS (56)
struct instr {
char mnem[4];
int opcode[INDIRECT + 1];
};
extern word lc;
extern int pass;
PRIVATE struct instr astab[NR_OF_MNEMS] = {
{"ADC", {-1, -1, 0x6d, 0x65, 0x69, 0x7d, 0x79, 0x61, 0x71, 0x75, -1, -1, -1}},
{"AND", {-1, -1, 0x2d, 0x25, 0x29, 0x3d, 0x39, 0x21, 0x31, 0x35, -1, -1, -1}},
{"ASL", {-1, 0x0a, 0x0e, 0x06, -1, 0x1e, -1, -1, -1, 0x16, -1, -1, -1}},
{"BCC", {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0x90, -1}},
{"BCS", {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0x80, -1}},
{"BEQ", {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0xf0, -1}},
{"BIT", {-1, -1, 0x2c, 0x24, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"BMI", {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0x30, -1}},
{"BNE", {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0xD0, -1}},
{"BPL", {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0x10, -1}},
{"BRK", {0x00, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"BVC", {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0x50, -1}},
{"BVS", {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0x70, -1}},
{"CLC", {0x18, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"CLD", {0xd8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"CLI", {0x58, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"CLV", {0xb8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"CMP", {-1, -1, 0xcd, 0xc5, 0xc9, 0xdd, 0xd9, 0xc1, 0xd1, 0xd5, -1, -1, -1}},
{"CPX", {-1, -1, 0xec, 0xe4, 0xe0, -1, -1, -1, -1, -1, -1, -1, -1}},
{"CPY", {-1, -1, 0xcc, 0xc4, 0xc0, -1, -1, -1, -1, -1, -1, -1, -1}},
{"DEC", {-1, -1, 0xce, 0xc6, -1, 0xde, -1, -1, -1, 0xd6, -1, -1, -1}},
{"DEX", {0xca, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"DEY", {0x88, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"EOR", {-1, -1, 0x4d, 0x45, 0x49, 0x5d, 0x59, 0x41, 0x51, 0x55, -1, -1, -1}},
{"INC", {-1, -1, 0xee, 0xe6, -1, 0xfe, -1, -1, -1, 0xf6, -1, -1, -1}},
{"INX", {0xe8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"INY", {0xc8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"JMP", {-1, -1, 0x4c, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0x6c}},
{"JSR", {-1, -1, 0x20, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"LDA", {-1, -1, 0xad, 0xa5, 0xa9, 0xbd, 0xb9, 0xa1, 0xb1, 0xb5, -1, -1, -1}},
{"LDX", {-1, -1, 0xae, 0xa6, 0xa2, -1, 0xbe, -1, -1, -1, 0xb6, -1, -1}},
{"LDY", {-1, -1, 0xac, 0xa4, 0xa0, 0xbc, -1, -1, -1, 0xb4, -1, -1, -1}},
{"LSR", {-1, 0x4a, 0x4e, 0x46, -1, 0x5e, -1, -1, -1, 0x56, -1, -1, -1}},
{"NOP", {0xea, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"ORA", {-1, -1, 0x0d, 0x05, 0x09, 0x1d, 0x19, 0x01, 0x11, 0x15, -1, -1, -1}},
{"PHA", {0x48, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"PHP", {0x08, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"PLA", {0x68, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"PLP", {0x28, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"ROL", {-1, 0x2a, 0x2e, 0x26, -1, 0x3e, -1, -1, -1, 0x36, -1, -1, -1}},
{"ROR", {-1, 0x6a, 0x6e, 0x66, -1, 0x7e, -1, -1, -1, 0x76, -1, -1, -1}},
{"RTI", {0x40, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"RTS", {0x60, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"SBC",
{-1, -1, 0xed, 0xe5, 0xe9, 0xfd, 0xf9, 0xe1, 0xf1, 0xf5, -1, -1, -1}},
{"SEC", {0x38, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"SED", {0xf8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"SEI", {0x78, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"STA", {-1, -1, 0x8d, 0x85, -1, 0x9d, 0x99, 0x81, 0x91, 0x95, -1, -1, -1}},
{"STX", {-1, -1, 0x8e, 0x86, -1, -1, -1, -1, -1, -1, 0x96, -1, -1}},
{"STY", {-1, -1, 0x8c, 0x84, -1, -1, -1, -1, -1, 0x94, -1, -1, -1}},
{"TAX", {0xaa, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"TAY", {0xa8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"TSX", {0xba, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"TXA", {0x8a, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"TXS", {0x9a, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}},
{"TYA", {0x98, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}}};
PRIVATE void bad_adrmode() { error("Illegal addressing mode"); }
#define CHECK_ADRMODE \
if (opcode == -1) { \
bad_adrmode(); \
return; \
}
PUBLIC void assemble(const char *mnem, adrmode adrmode, boolean external, void *id,
long num, boolean absolute) {
register int i;
int displ;
struct instr *ip;
int opcode;
int true_adrmode;
int sec;
for (i = 0; strcmp(mnem, astab[i].mnem) != 0 && i < NR_OF_MNEMS; i++)
;
if (i == NR_OF_MNEMS)
fatal("Unknown mnemonic %s passed lexical analysis", mnem);
ip = &astab[i];
opcode = ip->opcode[adrmode];
if (external) {
external_req(id, lc + 1);
}
if (ip->opcode[RELATIVE] != -1) { /* branch instr */
if (adrmode != ABSOLUTE) {
bad_adrmode();
return;
}
if (external) {
error("Target of branch instruction may not be externally defined");
return;
}
emit(ip->opcode[RELATIVE]);
displ = (int)(num - (long)lc + 1L);
if (displ > 127 || displ < -128) {
error("Target of branch out of reach");
}
emit(displ & 255);
return;
}
switch (adrmode) {
case IMPLIED:
case ACCUMULATOR:
CHECK_ADRMODE;
emit(opcode);
return;
case INDIRECT:
CHECK_ADRMODE;
emit(opcode);
emit2(num);
return;
case IMMEDIATE:
case INDX:
case INDY:
CHECK_ADRMODE;
emit(opcode);
emit(num);
return;
case ABSOLUTE:
sec = ZERO_PAGE;
break;
case ABSX:
sec = ZERO_PAGEX;
break;
case ABSY:
sec = ZERO_PAGEY;
default:
fatal("Unexpected addressing mode: ", adrmode);
}
true_adrmode = adrmode;
if (!external) {
if (pass == 1) {
if (num < 256) {
true_adrmode = sec;
}
} else {
opcode = getcode(lc);
if (opcode == ip->opcode[sec]) {
true_adrmode = sec;
} else if (opcode != ip->opcode[adrmode]) {
fatal("Internal error in assemble()");
}
}
}
emit(ip->opcode[true_adrmode]);
if (!absolute) {
reloc_req(lc);
}
if (adrmode == true_adrmode) {
emit2(num);
} else {
emit(num % 256);
}
}