From b0a652b10bd6a4b605cc3de66f6300188fd918f0 Mon Sep 17 00:00:00 2001
From: Nikita Smith <git.nikita.smith@gmail.com>
Date: Wed, 7 May 2025 11:36:54 -0700
Subject: [PATCH] helpers for parsing aux COFF symbols

---
 src/coff/coff_parse.c | 51 +++++++++++++++++++++++++++++++++++++++++++
 src/coff/coff_parse.h | 21 +++++++++++++-----
 2 files changed, 66 insertions(+), 6 deletions(-)

diff --git a/src/coff/coff_parse.c b/src/coff/coff_parse.c
index 3a53e8ba..f45723ad 100644
--- a/src/coff/coff_parse.c
+++ b/src/coff/coff_parse.c
@@ -121,6 +121,18 @@ coff_file_header_info_from_data(String8 raw_coff)
   return info;
 }
 
+internal COFF_SectionHeader **
+coff_section_table_from_data(Arena *arena, String8 data, Rng1U64 section_table_range)
+{
+  U64                  section_count = dim_1u64(section_table_range) / sizeof(COFF_SectionHeader);
+  COFF_SectionHeader **section_table = push_array_no_zero(arena, COFF_SectionHeader *, section_count+1);
+  section_table[0] = push_array(arena, COFF_SectionHeader, 1);
+  for (U64 i = 0; i < section_count; ++i) {
+    section_table[i+1] = str8_deserial_get_raw_ptr(data, section_table_range.min + i*sizeof(COFF_SectionHeader), sizeof(COFF_SectionHeader));
+  }
+  return section_table;
+}
+
 internal COFF_ParsedSymbol
 coff_parse_symbol32(String8 string_table, COFF_Symbol32 *sym32)
 {
@@ -131,6 +143,7 @@ coff_parse_symbol32(String8 string_table, COFF_Symbol32 *sym32)
   result.type              = sym32->type;
   result.storage_class     = sym32->storage_class;
   result.aux_symbol_count  = sym32->aux_symbol_count;
+  result.raw_symbol        = sym32;
   return result;
 }
 
@@ -150,6 +163,7 @@ coff_parse_symbol16(String8 string_table, COFF_Symbol16 *sym16)
   result.type             = sym16->type;
   result.storage_class    = sym16->storage_class;
   result.aux_symbol_count = sym16->aux_symbol_count;
+  result.raw_symbol       = sym16;
   return result;
 }
 
@@ -253,6 +267,43 @@ coff_interp_symbol(U32 section_number, U32 value, COFF_SymStorageClass storage_c
   return COFF_SymbolValueInterp_Regular;
 }
 
+internal void
+coff_parse_secdef(COFF_ParsedSymbol symbol, B32 is_big_obj, COFF_ComdatSelectType *selection_out, U32 *number_out, U32 *length_out, U32 *check_sum_out)
+{
+  Assert(coff_interp_symbol(symbol.section_number, symbol.value, symbol.storage_class) == COFF_SymbolValueInterp_Regular);
+  Assert(symbol.aux_symbol_count > 0);
+
+  if (is_big_obj) {
+    COFF_SymbolSecDef *sd = (COFF_SymbolSecDef *)((COFF_Symbol32 *)symbol.raw_symbol + 1);
+    if (selection_out) *selection_out = sd->selection;
+    if (length_out)    *length_out    = sd->length;
+    if (check_sum_out) *check_sum_out = sd->check_sum;
+    if (number_out)    *number_out    = sd->number_lo | ((U32)sd->number_hi << 16);
+  } else {
+    COFF_SymbolSecDef *sd = (COFF_SymbolSecDef *)((COFF_Symbol16 *)symbol.raw_symbol + 1);
+    if (selection_out) *selection_out = sd->selection;
+    if (length_out)    *length_out    = sd->length;
+    if (check_sum_out) *check_sum_out = sd->check_sum;
+    if (number_out)    *number_out    = sd->number_lo;
+  }
+}
+
+internal COFF_SymbolWeakExt *
+coff_parse_weak_tag(COFF_ParsedSymbol symbol, B32 is_big_obj)
+{
+  Assert(coff_interp_symbol(symbol.section_number, symbol.value, symbol.storage_class) == COFF_SymbolValueInterp_Weak);
+  Assert(symbol.aux_symbol_count > 0);
+
+  void *tag;
+  if (is_big_obj) {
+    tag = (COFF_SymbolWeakExt *)((COFF_Symbol32 *)symbol.raw_symbol + 1);
+  } else {
+    tag = (COFF_SymbolWeakExt *)((COFF_Symbol16 *)symbol.raw_symbol + 1);
+  }
+
+  return tag;
+}
+
 internal COFF_RelocNode *
 coff_reloc_list_push(Arena *arena, COFF_RelocList *list, COFF_Reloc reloc)
 {
diff --git a/src/coff/coff_parse.h b/src/coff/coff_parse.h
index 69c57ff3..b5990312 100644
--- a/src/coff/coff_parse.h
+++ b/src/coff/coff_parse.h
@@ -49,12 +49,13 @@ typedef struct COFF_Symbol32Array
 
 typedef struct COFF_ParsedSymbol
 {
-  String8              name;
-  U32                  value;
-  U32                  section_number;
-  COFF_SymbolType      type;
-  COFF_SymStorageClass storage_class;
-  U8                   aux_symbol_count;
+  String8               name;
+  U32                   value;
+  U32                   section_number;
+  COFF_SymbolType       type;
+  COFF_SymStorageClass  storage_class;
+  U8                    aux_symbol_count;
+  void                 *raw_symbol;
 } COFF_ParsedSymbol;
 
 typedef U32 COFF_SymbolValueInterpType;
@@ -247,6 +248,11 @@ internal B32 coff_is_big_obj(String8 raw_coff);
 internal B32 coff_is_obj    (String8 raw_coff);
 internal COFF_FileHeaderInfo coff_file_header_info_from_data(String8 raw_coff);
 
+////////////////////////////////
+// Section
+
+internal COFF_SectionHeader ** coff_section_table_from_data(Arena *arena, String8 data, Rng1U64 section_table_range);
+
 ////////////////////////////////
 // Symbol
 
@@ -261,6 +267,9 @@ internal COFF_Symbol16Node *coff_symbol16_list_push(Arena *arena, COFF_Symbol16L
 
 internal COFF_SymbolValueInterpType coff_interp_symbol(U32 section_number, U32 value, COFF_SymStorageClass storage_class);
 
+internal void coff_parse_secdef(COFF_ParsedSymbol symbol, B32 is_big_obj, COFF_ComdatSelectType *selection_out, U32 *number_out, U32 *length_out, U32 *check_sum_out);
+internal COFF_SymbolWeakExt * coff_parse_weak_tag(COFF_ParsedSymbol symbol, B32 is_big_obj);
+
 ////////////////////////////////
 // Reloc