meow

build

@@ -0,0 +1,9 @@
+#!/bin/sh
+#~/stuff/zig/zig cc -static -nostdlib -nodefaultlibs meow.s -o amogus || exit
+#gcc -static -nostdlib -nodefaultlibs meow.s -o amogus.o || exit
+gcc -c meow.s -o amogus.o || exit
+~/stuff/zig/zig cc -static -nostdlib -nodefaultlibs amogus.o -o amogus || exit
+#clang -static -nostdlib -nodefaultlibs meow.s -o amogus || exit
+objdump -d amogus
+strip -K entry amogus
+du -b amogus

meow.s

@@ -0,0 +1,84 @@
+.globl _start
+.type _start, @function
+.globl entry
+.type entry, @function
+_start:
+	#mov -4(%ebp),%eax
+	pop %rax
+	mov %rax,argc(%rip)
+	mov %rax,%rdi
+	pop %rax
+	mov %rax,argv(%rip)
+	cmp $1,%rdi
+	jg endif
+	mov $1,%rdi
+	call usage
+	jmp _exit
+endif:
+	
+	mov $0,%rdi
+	jmp _exit
+
+usage:
+	lea help0(%rip),%rdi
+	mov $help0l,%rsi
+
+	call write
+
+	mov [argv],%rdi
+	push %rdi
+	call strlen
+	pop %rdi
+	mov %rax,%rsi
+	call write
+
+	lea help1(%rip),%rdi
+	mov $help1l,%rsi
+	call write
+
+	ret
+
+# rdi - buf
+# -> rax - len
+strlen:
+	mov %rdi,%rax
+	strlen_loop:
+		movb 0(%rax),%sil
+		inc %rax
+		test %sil,%sil
+		jnz strlen_loop
+	sub $1,%rax
+	sub %rdi,%rax
+	ret
+
+# rdi - buf
+# rsi - len
+write:
+	push %rdi
+	push %rsi
+	pop %rdx
+	pop %rsi
+	mov $1,%rax
+	mov $1,%rdi
+	syscall
+	ret
+help0:
+	.ascii "Usage: "
+	.set help0l, .-help0
+help1:
+	.ascii " regex0 [regex1 ...]\nstdout: NUL-separated list of matching strings\n"
+	.set help1l, .-help1
+_exit:
+	mov $0x3c,%rax
+	syscall
+	ret
+entry:
+	ret
+
+.bss
+argc:
+	.zero 8
+argv:
+	.zero 8
+buf:
+	.zero 65536

test

@@ -0,0 +1,2 @@
+#!/bin/sh
+./build && gdb -iex 'set confirm no' -ex 'run' amogus