From 687dcc81de7bce5ea620ab1d76eac88febc93c2c Mon Sep 17 00:00:00 2001
From: Allen Webster <yoyo4thdimention@gmail.com>
Date: Sat, 3 Jul 2021 12:32:42 -0400
Subject: [PATCH] hand written c-style hex string from integer

---
 source/md.h      |  8 +++++---
 source/md_impl.c | 43 +++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/source/md.h b/source/md.h
index 5bb4fdb..2d889e6 100644
--- a/source/md.h
+++ b/source/md.h
@@ -774,9 +774,11 @@ MD_FUNCTION MD_String8 MD_PathChopLastSlash(MD_String8 string);
 
 //~ Numeric Strings
 
-MD_FUNCTION MD_u64         MD_U64FromString(MD_String8 string, MD_u32 radix);
-MD_FUNCTION MD_i64         MD_CStyleIntFromString(MD_String8 string);
-MD_FUNCTION MD_f64         MD_F64FromString(MD_String8 string);
+MD_FUNCTION MD_u64     MD_U64FromString(MD_String8 string, MD_u32 radix);
+MD_FUNCTION MD_i64     MD_CStyleIntFromString(MD_String8 string);
+MD_FUNCTION MD_f64     MD_F64FromString(MD_String8 string);
+
+MD_FUNCTION MD_String8 MD_CStyleHexStringFromU64(MD_u64 x, MD_b32 caps);
 
 //~ Enum/Flag Strings
 
diff --git a/source/md_impl.c b/source/md_impl.c
index 83696c8..c3e1e25 100644
--- a/source/md_impl.c
+++ b/source/md_impl.c
@@ -893,6 +893,45 @@ MD_F64FromString(MD_String8 string)
     return(atof(str));
 }
 
+
+MD_FUNCTION_IMPL MD_String8
+MD_CStyleHexStringFromU64(MD_u64 x, MD_b32 caps)
+{
+    static char md_int_value_to_char[] = "0123456789abcdef";
+    MD_u8 buffer[10];
+    MD_u8 *opl = buffer + 10;
+    MD_u8 *ptr = opl;
+    if (x == 0){
+        ptr -= 1;
+        *ptr = '0';
+    }
+    else{
+        for (;;){
+            MD_u32 val = x%16;
+            x /= 16;
+            MD_u8 c = (MD_u8)md_int_value_to_char[val];
+            if (caps){
+                c = MD_CharToUpper(c);
+            }
+            ptr -= 1;
+            *ptr = c;
+            if (x == 0){
+                break;
+            }
+        }
+    }
+    ptr -= 1;
+    *ptr = 'x';
+    ptr -= 1;
+    *ptr = '0';
+    
+    MD_String8 result = MD_ZERO_STRUCT;
+    result.size = (MD_u64)(ptr - buffer);
+    result.str = MD_PushArray(MD_u8, result.size);
+    MD_MemoryCopy(result.str, buffer, result.size);
+    return(result);
+}
+
 //~ Enum/Flag Strings
 
 MD_FUNCTION_IMPL MD_String8
@@ -1861,11 +1900,11 @@ MD_ParseOneNode(MD_String8 string, MD_u64 offset)
             switch (bad_token.kind){
                 case MD_TokenKind_BadCharacter:
                 {
-                    // TODO(allen): tighten up with good integer <-> string helpers
                     MD_String8List bytes = {0};
                     for(int i_byte = 0; i_byte < bad_token.raw_string.size; ++i_byte)
                     {
-                        MD_S8ListPush(&bytes, MD_S8Fmt("0x%02X", bad_token.raw_string.str[i_byte]));
+                        MD_u8 b = bad_token.raw_string.str[i_byte];
+                        MD_S8ListPush(&bytes, MD_CStyleHexStringFromU64(b, 1));
                     }
                     
                     MD_StringJoin join = MD_ZERO_STRUCT;