int read_ModR_M(swaddr_t eip, Operand *rm, Operand *reg) {
ModR_M m;
m.val = instr_fetch(eip, 1);
// Log("m.val = %02x", m.val);
reg->type = OP_TYPE_REG;
reg->reg = m.reg;
if(m.mod == 3) {
rm->type = OP_TYPE_REG;
rm->reg = m.R_M;
switch(rm->size) {
case 1: rm->val = reg_b(m.R_M); break;
case 2: rm->val = reg_w(m.R_M); break;
case 4: rm->val = reg_l(m.R_M); break;
default: assert(0);
}
#ifdef DEBUG
switch(rm->size) {
case 1: sprintf(rm->str, "%%%s", regsb[m.R_M]); break;
case 2: sprintf(rm->str, "%%%s", regsw[m.R_M]); break;
case 4: sprintf(rm->str, "%%%s", regsl[m.R_M]); break;
}
#endif
return 1;
}
else {
int instr_len = load_addr(eip, &m, rm);
rm->val = swaddr_read(rm->addr, rm->size, R_DS); //TODO DS or SS
return instr_len;
}
}
void print_bin_instr(swaddr_t eip, int len) {
int i;
int l = sprintf(asm_buf, "%8x: ", eip);
for(i = 0; i < len; i ++) {
l += sprintf(asm_buf + l, "%02x ", instr_fetch(eip + i, 1));
}
sprintf(asm_buf + l, "%*.s", 50 - (12 + 3 * len), "");
}
int mov_rm2sr(swaddr_t eip){
/* decode rm */
int len = decode_rm_w(eip + 1);
/* decode sreg */
uint8_t addr = instr_fetch(eip + 1, 1);
int sr_index = (addr >> 3) & 7;
cpu.Sreg[sr_index].val = op_src -> val;
/* set sreg base and limit */
uint64_t base_limit = decode_gdt(cpu.Sreg[sr_index].index);
cpu.Sreg[sr_index].base = base_limit >> 32;
cpu.Sreg[sr_index].limit = (base_limit << 32) >> 32;
return len+1;
}
static make_helper(_2byte_esc) {
eip ++;
uint32_t opcode = instr_fetch(eip, 1);
ops_decoded.opcode = opcode | 0x100;
return _2byte_opcode_table[opcode](eip) + 1;
}
int load_addr(swaddr_t eip, ModR_M *m, Operand *rm) {
assert(m->mod != 3);
int32_t disp;
int instr_len, disp_offset, disp_size = 4;
int base_reg = -1, index_reg = -1, scale = 0;
swaddr_t addr = 0;
if(m->R_M == R_ESP) {
SIB s;
s.val = instr_fetch(eip + 1, 1);
base_reg = s.base;
disp_offset = 2;
scale = s.ss;
if(s.index != R_ESP) { index_reg = s.index; }
/*
if (s.ss==0&&s.index==R_EBP){
rm->sreg=R_SS;
}
*/
}
else {
/* no SIB */
base_reg = m->R_M;
disp_offset = 1;
}
if (base_reg==R_ESP||base_reg==R_EBP){
rm->sreg=R_SS;
}else{
rm->sreg=R_DS;
}
if(m->mod == 0) {
if(base_reg == R_EBP) { base_reg = -1; }
else { disp_size = 0; }
}
else if(m->mod == 1) { disp_size = 1; }
instr_len = disp_offset;
if(disp_size != 0) {
/* has disp */
disp = instr_fetch(eip + disp_offset, disp_size);
if(disp_size == 1) { disp = (int8_t)disp; }
instr_len += disp_size;
addr += disp;
}
if(base_reg != -1) {
addr += reg_l(base_reg);
}
if(index_reg != -1) {
addr += reg_l(index_reg) << scale;
}
#ifdef DEBUG
char disp_buf[16];
char base_buf[8];
char index_buf[8];
if(disp_size != 0) {
/* has disp */
sprintf(disp_buf, "%s%#x", (disp < 0 ? "-" : ""), (disp < 0 ? -disp : disp));
}
else { disp_buf[0] = '\0'; }
if(base_reg == -1) { base_buf[0] = '\0'; }
else {
sprintf(base_buf, "%%%s", regsl[base_reg]);
}
if(index_reg == -1) { index_buf[0] = '\0'; }
else {
sprintf(index_buf, ",%%%s,%d", regsl[index_reg], 1 << scale);
}
if(base_reg == -1 && index_reg == -1) {
sprintf(rm->str, "%s", disp_buf);
}
else {
sprintf(rm->str, "%s(%s%s)", disp_buf, base_buf, index_buf);
}
#endif
rm->type = OP_TYPE_MEM;
rm->addr = addr;
return instr_len;
}
/* For more details about instruction format, please refer to i386 manual. */
int read_ModR_M(swaddr_t eip, swaddr_t *addr) {
ModR_M m;
m.val = instr_fetch(eip, 1);
int32_t disp;
int instr_len, disp_offset, disp_size;
int base_reg = -1, index_reg = -1, scale = 0;
/* When m.mod == 3, the instruction is not going to access memory.
* This situation should be handle before calling read_ModR_M().
* Therefore, m.mod should not be 3 here.
*/
assert(m.mod != 3);
disp_size = 4;
if(m.R_M == R_ESP) {
SIB s;
s.val = instr_fetch(eip + 1, 1);
base_reg = s.base;
disp_offset = 2;
scale = s.ss;
if(s.index != R_ESP) { index_reg = s.index; }
}
else {
/* no SIB */
base_reg = m.R_M;
disp_offset = 1;
}
if(m.mod == 0) {
if(base_reg == R_EBP) { base_reg = -1; }
else { disp_size = 0; }
}
else if(m.mod == 1) { disp_size = 1; }
char disp_buf[16];
char base_buf[8];
char index_buf[8];
instr_len = disp_offset;
*addr = 0;
if(disp_size != 0) {
/* has disp */
disp = instr_fetch(eip + disp_offset, disp_size);
if(disp_size == 1) { disp = (int8_t)disp; }
sprintf(disp_buf, "%s%#x", (disp < 0 ? "-" : ""), (disp < 0 ? -disp : disp));
instr_len += disp_size;
*addr += disp;
}
else { disp_buf[0] = '\0'; }
if(base_reg == -1) { base_buf[0] = '\0'; }
else {
sprintf(base_buf, "%%%s", regsl[base_reg]);
*addr += reg_l(base_reg);
}
if(index_reg == -1) { index_buf[0] = '\0'; }
else {
sprintf(index_buf, ",%%%s,%d", regsl[index_reg], 1 << scale);
*addr += reg_l(index_reg) << scale;
}
if(base_reg == -1 && index_reg == -1) {
print_ModR_M_asm("%s", disp_buf);
}
else {
print_ModR_M_asm("%s(%s%s)", disp_buf, base_buf, index_buf);
}
return instr_len;
}
/*
* @describe evaluate the expression and return the value
* @param {int, int} p, q
* @return {int} value
*/
uint32_t eval(int p, int q) {
if(p > q) {
/* Bad expression */
assert(0);
}
else if(p == q) {
/*
* Single token
* For now, this token should be a number
* return the value of the exprssion
*/
if(tokens[p].type == VAR) {
int res = find_var(tokens[p].str);
if(res == -1) {
printf("undefined reference to %s!\n", tokens[p].str);
return 0;
}
return res;
}
if(tokens[p].type == DEC_NUM) {
return atoi(tokens[p].str);
}
if(tokens[p].type == HEX_NUM) {
return strtol(tokens[p].str, NULL, 16);
}
if(tokens[p].type == REG) {
return getreg(tokens[p].str);
}
}
else if(check_parentness(p, q) == true) {
/*
* The expression is surrounded by a matched pair of parentheses.
* If that is the case, just throw away the parentheses.
*/
return eval(p + 1, q - 1);
}
else {
int i;
int j;
int op = -1;
int flag = 0; //操作符优先级标志
uint32_t val1;
uint32_t val2;
if(tokens[p].type == NEG) {
if(check_parentness(p + 1, q) || p + 1 == q) {
return -1 * eval(p + 1, q);
}
}
else if(tokens[p].type == DEREF) {
if(check_parentness(p + 1, q) || p + 1 == q) {
return instr_fetch(eval(p + 1, q), 1);
}
}
else if(tokens[p].type == '!') {
if(check_parentness(p + 1, q) || p + 1 == q) {
return !eval(p + 1, q);
}
}
for(i = p, j = 0; i <= q; i++) {
//操作符优先级
if(tokens[i].type == '(' ) {
j++;
}
else if(tokens[i].type == ')') {
j--;
}
else if(j == 0
&& (tokens[i].type == EQ || tokens[i].type == NEQ
|| tokens[i].type == LEQ || tokens[i].type == GEQ
|| tokens[i].type == L || tokens[i].type == G)) {
if(flag < 4) {
flag = 4;
op = i;
}
}
else if(j == 0
&& (tokens[i].type == AND || tokens[i].type == OR)) {
if(flag < 3) {
op = i;
flag = 3;
}
}
else if(j == 0
&& (tokens[i].type == '+' || tokens[i].type == '-')) {
if(flag < 2) {
op = i;
flag = 2;
}
}
else if(j == 0
&& (tokens[i].type == '*' || tokens[i].type == '/')) {
if(flag < 1) {
op = i;
flag = 1;
}
}
}
val1 = eval(p, op - 1);
val2 = eval(op + 1, q);
switch(tokens[op].type) {
case '+':
return val1 + val2;
break;
case '-':
return val1 - val2;
break;
case '*':
return val1 * val2;
break;
case '/':
if(val2 == 0) {
printf("Error\n");
break;
}
return val1 / val2;
break;
case EQ:
return val1 == val2 ? 1 : 0;
break;
case NEQ:
return val1 != val2 ? 1 : 0;
break;
case LEQ:
return val1 <= val2 ? 1 : 0;
break;
case GEQ:
return val1 >= val2 ? 1 : 0;
break;
case L:
return val1 < val2 ? 1 : 0;
break;
case G:
return val1 > val2 ? 1 : 0;
break;
case AND:
return val1 && val2;
break;
case OR:
return val1 || val2;
break;
default: assert(0);
}
}
return 0;
}