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#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <errno.h>
#include "parse.h"
static void disasm_rtype(uint16_t i, uint16_t unused, struct instruction *inst)
{
inst->type = INST_TYPE_R;
inst->inst.r.oper = GET_OPER(i);
inst->inst.r.dest = GET_REG_DEST(i);
inst->inst.r.left = GET_REG_LEFT(i);
inst->inst.r.right = GET_REG_RIGHT(i);
}
static void disasm_nitype(uint16_t i, uint16_t unused, struct instruction *inst)
{
inst->type = INST_TYPE_NI;
inst->inst.i.oper = GET_OPER(i);
inst->inst.i.dest = GET_REG_DEST(i);
inst->inst.i.left = GET_REG_LEFT(i);
inst->inst.i.imm.value = GET_NI_IMM(i);
inst->inst.i.imm_is_ident = 0;
}
static void disasm_witype(uint16_t i, uint16_t imm, struct instruction *inst)
{
inst->type = INST_TYPE_WI;
inst->inst.i.oper = GET_OPER(i);
inst->inst.i.dest = GET_REG_DEST(i);
inst->inst.i.left = GET_REG_LEFT(i);
inst->inst.i.imm.value = imm;
inst->inst.i.imm_is_ident = 0;
}
static void disasm_jreg(uint16_t i, uint16_t unused, struct instruction *inst)
{
inst->type = INST_TYPE_JR;
inst->inst.jr.cond = GET_JB_COND(i);
inst->inst.jr.reg = GET_JUMP_REG(i);
}
static void disasm_jimm(uint16_t i, uint16_t imm, struct instruction *inst)
{
inst->type = INST_TYPE_JI;
inst->inst.ji.cond= GET_JB_COND(i);
inst->inst.ji.imm.value = imm;
inst->inst.ji.imm_is_ident = 0;
}
static void disasm_bimm(uint16_t i, uint16_t pc, struct instruction *inst)
{
struct { signed int s:10; } sign;
int offset = sign.s = GET_B_OFFSET(i);
inst->type = INST_TYPE_B;
inst->inst.b.cond = GET_JB_COND(i);
inst->inst.b.imm.value = pc + 2 * offset;
inst->inst.b.imm_is_ident = 0;
}
/**
* FIXME move and factor out with parse.c */
static struct instruction *insts = NULL;
static size_t insts_count = 0;
static int add_instruction(struct instruction inst)
{
struct instruction *old_insts = insts;
insts = realloc(insts, (insts_count + 1) * sizeof(struct instruction));
if (!insts) {
free(old_insts);
perror("realloc");
return 1;
}
insts[insts_count] = inst;
insts_count++;
return 0;
}
/* FIXME needs whatsit arguments. f, tok, tok length */
static int disasm_file(FILE *f)
{
int ret = 0;
size_t offs = 0;
uint16_t inst = 0;
uint8_t c[2] = { 0 };
size_t extra_read = 0;
uint16_t extra_arg = 0;
struct instruction i = { 0 };
void (*disasm_inst)(uint16_t, uint16_t, struct instruction*);
while (!feof(f) && fread(c, sizeof(c), 1, f) == 1) {
extra_read = 0;
inst = c[0] << 8 | c[1];
switch (GET_INST_TYPE(inst)) {
case INST_TYPE_RTYPE:
disasm_inst = disasm_rtype;
break;
case INST_TYPE_NITYPE:
disasm_inst = disasm_nitype;
break;
case INST_TYPE_WITYPE:
if (fread(c, sizeof(c), 1, f) != 1) {
ret = -errno;
break;
}
extra_read = sizeof(c);
extra_arg = c[0] << 16 | c[1];
disasm_inst = disasm_witype;
break;
case INST_TYPE_JTYPE:
/* J Type can be split into three further subtypes:
* - branch (always immediate, 2 bytes)
* - jump reg (2 bytes)
* - jump immediate (4 bytes)
*/
if (inst & MASK_IS_BRANCH) {
disasm_inst = disasm_bimm;
extra_arg = offs;
} else {
if (inst & MASK_JR) {
disasm_inst = disasm_jreg;
} else {
if (fread(c, sizeof(c), 1, f) != 1) {
ret = -errno;
break;
}
extra_arg = c[0] << 16 | c[1];
extra_read = sizeof(c);
disasm_inst = disasm_jimm;
}
}
break;
default:
printf("Unhandled instruction at byte %zd\n", offs);
ret = -1;
break;
}
/* Fall out of loop if picking a handler errored */
if (ret) {
break;
}
disasm_inst(inst, extra_arg, &i);
if (ret < 0) {
fprintf(stderr, "Error handling instruction at byte %zd\n", offs);
break;
}
if (add_instruction(i))
return 1;
offs += sizeof(c) + extra_read;
}
if (!feof(f)) {
perror("fread");
ret = -errno;
}
return ret;
}
int disasm(FILE *f, struct instruction **i, size_t *i_count)
{
int ret = 0;
ret = disasm_file(f);
*i = insts;
*i_count = insts_count;
return ret;
}
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