From b65869a4dbaec4d237b17581b260eb0d48e4fcca Mon Sep 17 00:00:00 2001
From: Andreas Baumann <mail@andreasbaumann.cc>
Date: Wed, 29 Jul 2020 18:26:31 +0200
Subject: ec: can generate binaries for the simple emulator as well as ELF
 binaries the Linux 386 host

---
 ecomp-c/ec.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 88 insertions(+), 3 deletions(-)

diff --git a/ecomp-c/ec.c b/ecomp-c/ec.c
index dd95fe7..bc0944e 100644
--- a/ecomp-c/ec.c
+++ b/ecomp-c/ec.c
@@ -19,6 +19,13 @@ enum {
 static int DEBUG_GETCHAR = 0;
 static int DEBUG_SCANNER = 0;
 
+typedef enum {
+	BINARY_FORMAT_EMUL = 0,
+	BINARY_FORMAT_ELF = 1
+} BinaryFormat;
+
+static BinaryFormat binary_format = BINARY_FORMAT_EMUL;
+
 /* scanner */
 
 typedef enum {
@@ -2044,7 +2051,7 @@ static void init( void )
 	sym = getSym( );
 }
 
-static void prologue( void )
+static void prologue_emul( void ) 
 {
 	/* fasm or asm-i386 syntax */
 	Emit( "format binary\n" );
@@ -2052,6 +2059,58 @@ static void prologue( void )
 	Emit( "org $1000000\n" );
 }
 
+static void prologue_elf( void )
+{
+	/* fasm, i386, ELF, Linux */
+	Emit( "format binary\n" );
+	Emit( "use32\n" );
+	Emit( "org $08048000\n" );
+	Emit( "ehdr:\n" );
+	Emit( "db $7F, \"ELF\"\n" );
+	Emit( "db 1\n" );
+	Emit( "db 1\n" );
+	Emit( "db 1\n" );
+	Emit( "db 0\n" );
+	Emit( "dd 0, 0\n" );
+	Emit( "dw 2\n" );
+	Emit( "dw 3\n" );
+	Emit( "dd 1\n" );
+	Emit( "dd _start\n" );
+	Emit( "dd phdr - $$\n" );
+	Emit( "dd 0\n" );
+	Emit( "dd 0\n" );
+	Emit( "dw ehdrsize\n" );
+	Emit( "dw phdrsize\n" );
+	Emit( "dw 1\n" );
+	Emit( "dw 0\n" );
+	Emit( "dw 0\n" );
+	Emit( "dw 0\n" );
+	Emit( "ehdrsize = $ - ehdr\n" );
+	Emit( "phdr:\n" );
+	Emit( "dd 1\n" );
+	Emit( "dd 0\n" );
+	Emit( "dd $$\n" );
+	Emit( "dd $$\n" );
+	Emit( "dd filesize\n" );
+	Emit( "dd filesize\n" );
+	Emit( "dd 7\n" );
+	Emit( "dd $1000\n" );
+	Emit( "phdrsize = $ - phdr\n" );
+	Emit( "_start:");
+}
+
+static void prologue( void )
+{
+	switch( binary_format ) {
+		case BINARY_FORMAT_EMUL:
+			prologue_emul( );
+			break;
+		case BINARY_FORMAT_ELF:
+			prologue_elf( );
+			break;
+	}
+}
+
 static void reserve_initialize( Symbol *symbol )
 {
 	int i;
@@ -2119,11 +2178,10 @@ static void reserve_initialize( Symbol *symbol )
 	}
 }
 
-static void epilogue( void )
+static void Emit_symbols( void )
 {
 	Symbol *symbol;
 	
-	Emit( "hlt\n" );
 	symbol = global_scope->symbol;
 	while( symbol != NULL ) {
 		if( symbol->class == SYMBOL_CLASS_VARIABLE ) {
@@ -2134,6 +2192,33 @@ static void epilogue( void )
 	}
 }
 
+static void epilogue_emul( void )
+{
+	Emit( "hlt\n" );
+	Emit_symbols( );
+}
+
+static void epilogue_elf( void )
+{
+	Emit( "mov ebx, 0\n" );
+	Emit( "mov eax, 1\n" );
+	Emit( "int $80\n" );
+	Emit_symbols( );
+	Emit( "filesize = $ - $$\n" );
+}
+
+static void epilogue( void )
+{
+	switch( binary_format ) {
+		case BINARY_FORMAT_EMUL:
+			epilogue_emul( );
+			break;
+		case BINARY_FORMAT_ELF:
+			epilogue_elf( );
+			break;
+	}
+}
+
 static void deinit( void )
 {
 	free_scope( global_scope );
-- 
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