/* implementation */

static int iscallret(RDebug *dbg, ut64 addr) {
	ut8 buf[32];
	if (addr == 0LL || addr == UT64_MAX)
		return 0;
	/* check if region is executable */
	/* check if previous instruction is a call */
	/* if x86 expect CALL to be 5 byte length */
	if (dbg->arch && !strcmp (dbg->arch, "x86")) {
		(void)dbg->iob.read_at (dbg->iob.io, addr-5, buf, 5);
		if (buf[0] == 0xe8) {
			return 1;
		}
		if (buf[3] == 0xff  /* bits 4-5 (from right) of next byte must be 01 */
				&& ((buf[4] & 0xf0) == 0xd0  /* Mod is 11 */
					|| ((buf[4] & 0xf0) == 0x10  /* Mod is 00 */
						&& (buf[4] & 0x06) != 0x04))) {  /* R/M not 10x */
			return 1;
		}
		// IMMAMISSINGANYOP
	} else {
		RAnalOp op;
		(void) dbg->iob.read_at (dbg->iob.io, addr-8, buf, 8);
		(void) r_anal_op (dbg->anal, &op, addr-8, buf, 8, R_ARCH_OP_MASK_BASIC);
		if (op.type == R_ANAL_OP_TYPE_CALL || op.type == R_ANAL_OP_TYPE_UCALL) {
			return 1;
		}
		/* delay slot */
		(void) r_anal_op (dbg->anal, &op, addr-4, buf, 4, R_ARCH_OP_MASK_BASIC);
		if (op.type == R_ANAL_OP_TYPE_CALL || op.type == R_ANAL_OP_TYPE_UCALL) {
			return 1;
		}
	}
	return 0;
}

static RList *backtrace_fuzzy(RDebug *dbg, ut64 at) {
	ut8 *ptr;
	const int wordsize = dbg->bits / 8;
	ut64 sp;
	RIOBind *bio = &dbg->iob;
	int i;
	ut64 *p64, addr = 0LL;
	ut32 *p32;
	ut16 *p16;
	ut64 cursp, oldsp;
	RList *list;

	const int stacksize = 1024 * 512; // 512KB .. should get the size from the regions if possible
	ut8 *stack = malloc (stacksize);
	if (!stack) {
		return NULL;
	}
	if (at == UT64_MAX) {
		RRegItem *ri;
		RReg *reg = dbg->reg;
		const char *spname = r_reg_alias_getname (reg, R_REG_ALIAS_SP);
		if (!spname) {
			R_LOG_ERROR ("Cannot find stack pointer register");
			free (stack);
			return NULL;
		}
		ri = r_reg_get (reg, spname, R_REG_TYPE_GPR);
		if (!ri) {
			R_LOG_ERROR ("Cannot find stack pointer register");
			free (stack);
			return NULL;
		}
		sp = r_reg_get_value (reg, ri);
	} else {
		sp = at;
	}

	list = r_list_new ();
	list->free = free;
	cursp = oldsp = sp;
	(void)bio->read_at (bio->io, sp, stack, stacksize);
	ptr = stack;
	for (i = 0; i < dbg->btdepth; i++) {
		p64 = (ut64*)ptr;
		p32 = (ut32*)ptr;
		p16 = (ut16*)ptr;
		switch (wordsize) {
		case 8: addr = *p64; break;
		case 4: addr = *p32; break;
		case 2: addr = *p16; break;
		default:
			R_LOG_ERROR ("Invalid word size with asm.bits");
			r_list_free (list);
			free (stack);
			return NULL;
		}
		if (iscallret (dbg, addr)) {
			RDebugFrame *frame = R_NEW0 (RDebugFrame);
			frame->addr = addr;
			frame->size = cursp - oldsp;
			frame->sp = cursp;
			frame->bp = oldsp; //addr + (i * wordsize); // -4 || -8
			// R_LOG_DEBUG ("--------------> 0x%llx (%d)", addr, frame->size);
			r_list_append (list, frame);
			oldsp = cursp;
		}
		ptr += wordsize;
		cursp += wordsize;
	}
	free (stack);
	return list;
}
