From f7d14ea364fc7d592cfe6e5664b3bc7ad72b7804 Mon Sep 17 00:00:00 2001
From: Andreas Baumann <mail@andreasbaumann.cc>
Date: Sat, 18 Jul 2020 21:49:29 +0200
Subject: playing with small elf binaries in assembly

---
 ecomp-c/README                 |  5 +++++
 ecomp-c/asm-i386.c             | 14 ++++++++++++--
 ecomp-c/tests/asm-i386/elf.asm | 39 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 ecomp-c/tests/asm-i386/elf.asm

diff --git a/ecomp-c/README b/ecomp-c/README
index 4e1e88c..0f8e907 100644
--- a/ecomp-c/README
+++ b/ecomp-c/README
@@ -122,6 +122,11 @@ C compiler). We prefer the hierarchical approach
 
 one file per assembly file, load at fixed ORG (sort of in a.out style).
 
+another assembler, 0:15:00
+
+neested functions allow more efficient compiling as local scopes can
+be dropped and their local symbols.
+
 syscalls
 --------
 
diff --git a/ecomp-c/asm-i386.c b/ecomp-c/asm-i386.c
index 431ed52..fc91130 100644
--- a/ecomp-c/asm-i386.c
+++ b/ecomp-c/asm-i386.c
@@ -70,8 +70,8 @@ enum {
 };
 
 static int DEBUG_GETCHAR = 0;
-static int DEBUG_SCANNER = 0;
-static int DEBUG_PARSER = 0;
+static int DEBUG_SCANNER = 1;
+static int DEBUG_PARSER = 1;
 
 /* scanner */
 
@@ -88,6 +88,8 @@ typedef enum {
 	S_comma,
 	S_lbrak,
 	S_rbrak,
+	S_plus,
+	S_minus,
 	S_eof
 } S_Symbol;
 
@@ -104,6 +106,8 @@ static char *symname[S_eof+1] = {
 	",",
 	"[",
 	"]",
+	"+",
+	"-",
 	"eof"
 };
 
@@ -385,6 +389,12 @@ static S_Symbol getSym( void )
 			number( );
 			s = S_number;
 			break;
+		case '-':
+			s = S_minus;
+			break;
+		case '+':
+			s = S_plus;
+			break;
 		case 'f':
 			identifier( );
 			if( strcmp( ident, "format" ) == 0 ) {
diff --git a/ecomp-c/tests/asm-i386/elf.asm b/ecomp-c/tests/asm-i386/elf.asm
new file mode 100644
index 0000000..16f40e1
--- /dev/null
+++ b/ecomp-c/tests/asm-i386/elf.asm
@@ -0,0 +1,39 @@
+format binary
+use32
+org	$08048000
+ehdr:
+db	$7F, "ELF"	; e_ident: magic
+db	1		; EI_CLASS: ELFCLASS32
+db	1		; EI_BYTE: ELFDATA2LSB (little endian, 2's complement)
+db	1		; version of the object file format
+db	0		; EI_VERSION: EV_CURRENT, ABI version
+dd	0, 0		; EI_PAD: padding
+dw	2		; e_type: executable
+dw	3		; e_machine: Intel 80386
+dd	1		; e_version: current version
+dd	_start		; e_entry: entry address to _start
+dd	phdr - $$	; e_phoff: program header offset at phdr - current position
+dd	0		; e_shoff, no section header table
+dd	0		; e_flags
+dw	ehdrsize	; e_hsize: header size
+dw	phdrsize	; e_phentsize: size of a program header entry
+dw	1		; e_phnum: 1 entry in the program header table
+dw	0		; e_shentsize
+dw	0		; e_shnum
+dw	0		; e_shstrndx
+ehdrsize = $ - ehdr
+phdr:
+dd	1		; e_type: PT_LOAD
+dd	0		; e_offset
+dd	$$		; p_vaddr
+dd	0		; p_paddr
+dd	filesize	; p_filesz
+dd	filesize	; p_memsz
+dd	5		; p_flags: Read & Execute
+dd	0x1000		; p_align
+phdrsize = $ - phdr
+_start:	
+mov eax, 1
+mov ebx, 42
+int $80
+filesize = $ - $$
-- 
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