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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)
{
(void)unused;
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)
{
(void)unused;
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)
{
(void)unused;
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;
}
size_t disasm_single(struct instruction *i, uint16_t pc, uint16_t inst, uint16_t extra)
{
int ret = 0;
int extra_used = 0;
void (*disasm_inst)(uint16_t, uint16_t, struct instruction*);
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:
disasm_inst = disasm_witype;
extra_used = 1;
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;
/* hack PC into handler. It's expecting it */
extra = pc;
} else {
if (inst & MASK_JR) {
disasm_inst = disasm_jreg;
} else {
disasm_inst = disasm_jimm;
extra_used = 1;
}
}
break;
default:
ret = -EINVAL;
break;
}
if (!ret) {
disasm_inst(inst, extra, i);
/* positive return code is bytes consumed */
ret = extra_used ? 4 : 2;
}
return ret;
}
static int disasm_file(FILE *f)
{
int ret = 0;
size_t offs = 0;
uint16_t inst = 0;
uint16_t extra = 0;
uint8_t c[4] = { 0 };
size_t to_read = 0;
size_t nread = 0;
struct instruction i = { 0 };
/* prime the pump with two words read */
to_read = 4;
do {
nread = fread(c, 1, to_read, f);
switch (nread) {
case 0:
if (to_read == 2) {
/* use up what's left in extra */
} else {
/* just used up 4 bytes, and couldn't read more. break out*/
goto read_eof;
}
/* FALLTHROUGH */
case 2:
/* have just read 2 bytes: shift down and pack new in */
inst = extra;
extra = c[0] << 8 | c[1];
break;
case 4:
/* have just read 4 bytes: fresh inst and extra needed */
inst = c[0] << 8 | c[1];
extra = c[2] << 8 | c[3];
break;
default:
fprintf(stderr, "Internal error: unexpected nread '%zd'\n", nread);
return 1;
}
ret = disasm_single(&i, offs, inst, extra);
if (ret <= 0) {
fprintf(stderr, "Error handling instruction at byte %zd\n", offs);
break;
}
if (add_instruction(i))
return 1;
/* return value from disasm_single is # bytes decoded. Current byte
* offset is adjusted by this, and we need to read this many more bytes
* next time around */
offs += ret;
to_read = ret;
} while (!feof(f));
read_eof:
if (!feof(f)) {
perror("fread");
ret = -errno;
}
return 0;
}
int input_bin(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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