From 6fc645c9d281bcfd018423f113a90541709b336f Mon Sep 17 00:00:00 2001
From: Kevin Trogant <kevin_trog@proton.me>
Date: Wed, 3 Dec 2025 17:29:26 +0100
Subject: [PATCH] parse s8 to int

---
 rtcore.h | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 test.c   | 16 +++++++++++
 2 files changed, 102 insertions(+)

diff --git a/rtcore.h b/rtcore.h
index 573726b..36705ad 100644
--- a/rtcore.h
+++ b/rtcore.h
@@ -215,6 +215,14 @@ RTC_API split_result S8Split(s8 s, u8 c);
 /* Creates a clone of string s on arena a */
 RTC_API s8 S8Clone(s8 s, arena *a);
 
+typedef struct { i64 i; b32 ok; } s8_parse_i64_result;
+typedef struct { i32 i; b32 ok; } s8_parse_i32_result;
+
+/* Parses a integer from string s */
+RTC_API s8_parse_i64_result S8ParseI64(s8 s, int base);
+/* Parses an integer from string s */
+RTC_API s8_parse_i32_result S8ParseI32(s8 s, int base);
+
 /* Basic file io */
 typedef struct file_buffer
 {
@@ -392,6 +400,84 @@ S8Clone(s8 s, arena *a)
 	memcpy(c.data, s.data, s.length);
 	return s;
 }
+RTC_API s8_parse_i64_result
+S8ParseI64(s8 s, int base)
+{
+  isize at = s.length - 1;
+  i64 exp = 1;
+  i64 val = 0;
+  while (at >= 0)
+  {
+    u8 c = s.data[at];
+    int digit = 0;
+    if (c >= '0' && c <= '9')
+      digit = c - '0';
+    else if (c >= 'A' && c <= 'Z')
+      digit = c - 'A';
+    else if (c >= 'a' && c <= 'z')
+      digit = c - 'a';
+    else if (c == '-')
+    {
+      val *= -1;
+      break;
+    }
+    else if (c == '+')
+    {
+      break;
+    }
+    else
+      return (s8_parse_i64_result){0};
+    if (digit >= base)
+    	return (s8_parse_i64_result){0};
+    
+    val += digit * exp;
+    exp *= base;
+    --at;
+  }
+  return (s8_parse_i64_result){
+		.i = val,
+		.ok = 1,
+	};
+}
+RTC_API s8_parse_i32_result
+S8ParseI32(s8 s, int base)
+{
+  isize at = s.length - 1;
+  i32 exp = 1;
+  i32 val = 0;
+  while (at >= 0)
+  {
+    u8 c = s.data[at];
+    int digit = 0;
+    if (c >= '0' && c <= '9')
+      digit = c - '0';
+    else if (c >= 'A' && c <= 'Z')
+      digit = c - 'A';
+    else if (c >= 'a' && c <= 'z')
+      digit = c - 'a';
+    else if (c == '-')
+    {
+      val *= -1;
+      break;
+    }
+    else if (c == '+')
+    {
+      break;
+    }
+    else
+      return (s8_parse_i32_result){0};
+    if (digit >= base)
+    	return (s8_parse_i32_result){0};
+    
+    val += digit * exp;
+    exp *= base;
+    --at;
+  }
+  return (s8_parse_i32_result){
+		.i = val,
+		.ok = 1,
+	};
+}
 
 /* Basic file io */
 RTC_API file_buffer
diff --git a/test.c b/test.c
index 2e688a3..4d3ed96 100644
--- a/test.c
+++ b/test.c
@@ -47,6 +47,20 @@ ThreadTest(void)
   return AtomicLoad(&p) == 42;
 }
 
+internal int
+ParseIntTest(void)
+{
+  if (S8ParseI32(S8("123"), 10).i != 123)
+    return 0;
+  if (S8ParseI32(S8("-124"), 10).i != -124)
+    return 0;
+  if (S8ParseI64(S8("9223372036854775807"), 10).i != 9223372036854775807)
+    return 0;
+  if (S8ParseI32(S8("Not a number"), 10).ok)
+    return 0;
+  return 1;
+}
+
 int
 main()
 {
@@ -56,5 +70,7 @@ main()
     return 2;
   if (!ThreadTest())
     return 3;
+  if (!ParseIntTest())
+    return 4;
   return 0;
 }