From 63a374cf54c5b5d5a309421ab647b5e659406ad9 Mon Sep 17 00:00:00 2001
From: Nikita Smith <git.nikita.smith@gmail.com>
Date: Wed, 7 May 2025 10:01:21 -0700
Subject: [PATCH] simplify COFF reloc apply helper

---
 src/coff/coff.c | 33 +++++++++++++--------------------
 src/coff/coff.h |  8 ++++++++
 2 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/src/coff/coff.c b/src/coff/coff.c
index c2ab20a1..7d6fb166 100644
--- a/src/coff/coff.c
+++ b/src/coff/coff.c
@@ -179,18 +179,17 @@ coff_apply_size_from_reloc(COFF_MachineType machine, COFF_RelocType x)
   return 0;
 }
 
-internal void
-coff_apply_reloc_x64(String8        data,
-                     COFF_Reloc_X64 type,
-                     U64            apply_off,
-                     U64            reloc_virtual_offset,
-                     U32            symbol_section_number,
-                     U32            symbol_section_offset,
-                     U32            symbol_virtual_offset,
-                     U64            symbol_address)
+internal COFF_RelocValue
+coff_pick_reloc_value_x64(COFF_Reloc_X64 type,
+                          U64            reloc_virtual_offset,
+                          U32            symbol_section_number,
+                          U32            symbol_section_offset,
+                          U32            symbol_virtual_offset,
+                          U64            symbol_address)
 {
   U64 reloc_value_size = 0;
   S64 reloc_value      = 0;
+
   switch (type) {
   case COFF_Reloc_X64_Abs: {} break;
   case COFF_Reloc_X64_Addr64: {
@@ -199,7 +198,7 @@ coff_apply_reloc_x64(String8        data,
   } break;
   case COFF_Reloc_X64_Addr32: {
     reloc_value_size = 4;
-    reloc_value      = safe_cast_u32(symbol_address);
+    reloc_value      = symbol_address;
   } break;
   case COFF_Reloc_X64_Addr32Nb: {
     reloc_value_size = 4;
@@ -254,17 +253,11 @@ coff_apply_reloc_x64(String8        data,
   } break;
   }
 
-  // read addend
-  Assert(apply_off + reloc_value_size <= data.size);
-  U64 raw_addend = 0;
-  str8_deserial_read(data, apply_off, &raw_addend, reloc_value_size, reloc_value_size);
+  COFF_RelocValue result = {0};
+  result.size            = reloc_value_size;
+  result.value           = reloc_value;
 
-  // compute new reloc value
-  S64 addend       = extend_sign64(raw_addend, reloc_value_size);
-  U64 reloc_result = reloc_value + addend;
-  
-  // commit new reloc value
-  MemoryCopy(data.str + apply_off, &reloc_result, reloc_value_size);
+  return result;
 }
 
 internal String8
diff --git a/src/coff/coff.h b/src/coff/coff.h
index 34475016..89445216 100644
--- a/src/coff/coff.h
+++ b/src/coff/coff.h
@@ -576,6 +576,12 @@ typedef struct COFF_ImportHeader
 
 #pragma pack(pop)
 
+typedef struct COFF_RelocValue
+{
+  U64 size;
+  S64 value;
+} COFF_RelocValue;
+
 ////////////////////////////////
 // Section
 
@@ -596,6 +602,8 @@ internal String8 coff_read_symbol_name(String8 string_table, COFF_SymbolName *na
 internal U64 coff_apply_size_from_reloc_x64(COFF_Reloc_X64 x);
 internal U64 coff_apply_size_from_reloc_x86(COFF_Reloc_X86 x);
 
+internal COFF_RelocValue coff_pick_reloc_valuex64(COFF_Reloc_X64 type, U64 reloc_virtual_offset, U32 symbol_section_number, U32 symbol_section_offset, U32 symbol_virtual_offset, U64 symbol_address);
+
 ////////////////////////////////
 // Import