From fc56815f74f4ae94fb03418917041047c425c203 Mon Sep 17 00:00:00 2001
From: ALittlePatate <maxime@patate.dev>
Date: Sat, 5 Aug 2023 19:49:39 +0200
Subject: [PATCH] add return stack

now we can jump where we want
---
 docs/documentation.md | 18 +-----------------
 src/instructions.c    | 26 ++++++++++++++++++++++----
 2 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/docs/documentation.md b/docs/documentation.md
index 6dcb5c3..4fce0fc 100644
--- a/docs/documentation.md
+++ b/docs/documentation.md
@@ -95,22 +95,6 @@ Note that return can be used in a conditional jump like so :
 cmp a1, 5
 je return ; note it's return and not ret when used like this
 ```
-Due to current limitations, you can't jump to more than one function and return to the right place. Example :
-```asm
-bar:
-add a1, 2
-ret
-
-foo:
-add a1, 3
-jmp bar
-ret
-
-main:
-jmp foo
-; more code
-```
-Here `foo` will never return to the main function and will instead return to `ret`. TOFIX !!
 
 ### Calling APIs
 APIs can be added in the [api.c](https://github.com/ALittlePatate/pasm/blob/main/src/api.c) and [api.h](https://github.com/ALittlePatate/pasm/blob/main/src/api.h) files.
@@ -124,7 +108,7 @@ Here is a list of all the errors you can encounter and how to fix them :
 * `wrong number of arguments on line X` : you have more or less arguments needed for an operand, see [table](#syntax).
 * `arg1/arg2 is invalid on line X` : the operand used can't work with the type of argument provided (register/number/char)
 * `X is not a valid label/api` : you tried to jump (`jmp`) or `call` an undefined label or non-existing API. Check [Scripts structure](scripts-structure).
-* `stack overflow on line X` : you pushed to many times without poping.
+* `stack overflow on line X` : you pushed to many times without poping or you reached the recursion depth limit.
 * `stack underflow on line X` : you poped to many times without pushing.
 
 ## Running a script
diff --git a/src/instructions.c b/src/instructions.c
index 97143d9..94470e5 100644
--- a/src/instructions.c
+++ b/src/instructions.c
@@ -5,6 +5,8 @@
 #include <stdlib.h>
 #include <string.h>
 
+int RET_STACK[STACK_SIZE] = {-1*STACK_SIZE};
+int RET_STACK_IDX = 0;
 bool is_reg(char* arg) {
 	return (strcmp(arg, "eax") == 0) || (((arg[0] == 'a' && '0' <= arg[1] <= '9')) && strlen(arg) == 2);
 }
@@ -93,17 +95,33 @@ void cmp() {
 	return;
 }
 
-int line_should_ret = -1;
+int CheckRetStack() {
+	if (RET_STACK_IDX > STACK_SIZE) {
+		last_stack_code = OVERFLOW;
+		return 0;
+	}
+	if (RET_STACK_IDX < 0) {
+		last_stack_code = UNDERFLOW;
+		return 0;
+	}
+	
+	return 1;
+}
+
 void ret() {
-	if (line_should_ret == -1) {
+	if (!CheckRetStack()) return;
+	
+	if (RET_STACK[RET_STACK_IDX] == -1) {
 		exit_code = 1;
 		return;
 	}
 
-	fseek(fptr, line_should_ret, SEEK_SET);
+	fseek(fptr, RET_STACK[RET_STACK_IDX--], SEEK_SET);
 }
 
 void jmp() {
+	if (!CheckRetStack()) return;
+
 	if (strcmp(args->arg1, "return") == 0) {
 		ret();
 		return;
@@ -113,7 +131,7 @@ void jmp() {
 	for (int i = 0; i < MAX_LABEL; i++) {
 		if (labels[i] == NULL) break;
 		if (strcmp(args->arg1, labels[i]) == 0) {
-			line_should_ret = (int)char_read;
+            RET_STACK[RET_STACK_IDX++] = (int)char_read;
 			fseek(fptr, labels_lines[i], SEEK_SET);
 			char_read = labels_lines[i];
 			return;