1 files changed, 124 insertions, 0 deletions
diff --git a/prog5.asm b/prog5.asm
new file mode 100644
index 0000000..ae6b582
--- /dev/null
+++ b/prog5.asm
@@ -0,0 +1,124 @@
+; Gotta get these loops down... seriously.
+; Let's try to write a more manual puts function
+
+section .text
+global _start
+
+print_newline:
+	push ebp		; push previous function frame pointer into stack
+	mov ebp, esp	; assign new frame pointer
+
+	pusha			; save all registers
+	
+	mov eax, 4		; linux write syscall
+	mov ebx, 1		; stdout
+	mov ecx, LF		; newline char
+	mov edx, 2		; 2 bytes long
+	int 80h
+
+	popa			; restore all registers
+
+	leave			; restore stack frame
+	ret
+
+putc:
+	; purpose:
+	;	print character
+	; arguments:
+	;	ECX - character address
+	push ebp		; push previous function frame pointer into stack
+	mov ebp, esp	; assign new frame pointer
+	pusha			; save all registers, we're about to use them up
+
+	mov eax, 4		; linux write syscall
+	mov ebx, 1		; stdout
+	mov edx, 1
+	int 80h
+
+	popa			; restore all registers
+	leave			; restore stack frame
+	ret
+
+puts:
+	; purpose:
+	;	print a NULL terminated string followed by a new line
+	;	... character-by-character
+	; arguments:
+	;	ECX - char. string
+
+	push ebp
+	mov ebp, esp
+
+	.loop:
+		mov al, [ecx]	; copy current char into 8-bit register
+		inc ecx			; increment pointer
+		mov [char], al	; copy 8-bit character into `char` variable
+		
+		push eax		; save eax, we're modifying EAX (via al)
+		push ecx		; save ecx, to replace/send single char reference
+
+		mov ecx, char	; putc expects ECX to have a "string" so
+						; copy the character into the register
+
+		call putc		; print character to display
+
+						; REMEMBER THE ORDER OF PUSHES
+		pop ecx			; restore registers
+		pop eax			; ...
+
+		cmp al, 0		; check for NULL terminator
+		jz .break		; if al == 0: break loop
+		jmp .loop		; else: repeat
+	
+	.break:
+		call print_newline	; pretend this is C... eh?
+		leave				; restore stack
+		ret
+	
+exit:
+	mov eax, 1			; linux function, terminate
+	mov ebx, 0			; return value
+	int 80h				; linux kernel syscall
+	ret
+
+
+display_copyright:
+	push ebp
+	mov ebp, esp
+	push ecx
+
+	mov ecx, copyright
+	call puts
+	
+	pop ecx
+	leave
+	ret
+
+
+display_version:
+	push ebp
+	mov ebp, esp
+	
+	mov ecx, version
+	call puts
+
+	leave
+	ret
+
+
+_start:
+	call display_copyright
+	call display_version
+
+	call exit
+	ret
+
+
+section .data
+copyright	db	'Joseph Hunkeler (c) 2015,', 32
+				db	'All things reserved and whatever.', 0
+version		db	'Version 1.0.0'
+LF		db	13, 10	; ascii newline
+
+section .bss
+char	resb	1	; reserve one byte for 'puts' to use as a buffer