; By Chris Aubut (psyba.ppc@gmail.com)
; Remove .txt suffix
; Make with "gcc -o hexDump hexDump.S"
; Run with "hexDump < fileToHexDump"

#define		r_buf		r10
#define		r_out		r11
#define		r_end		r12

.align 2
.data

	buf:		.byte   0x00
	out:		.ascii  "0x00 "
	end:		.ascii  "\n"

.align 2
.text

	.globl _main
	_main:
	
		; preload addresses
		lis		r_buf, hi16(buf)
		ori		r_buf, r_buf, lo16(buf)
		
		lis		r_out, hi16(out)
		ori		r_out, r_out, lo16(out)
			
		lis		r_end, hi16(end)
		ori		r_end, r_end, lo16(end)
					
		_loop:
		
			; read in next byte
			li		r0, 3
			li		r3, 0
			addi	r4, r_buf, 0
			li		r5, 1
			sc
			nop
			
			; test for last byte
			addi	r4, r_buf, 0
			lbz		r6, 0(r4)
			cmpi	cr7, r3, 0
			beq		cr7, _finish
			
			; digit 1 to ascii
			srwi	r6, r6, 4
			cmpi	cr7, r6, 10
			blt		cr7, _digit1
			addi	r6, r6, 39
			_digit1:
				addi	r6, r6, 48
				addi	r4, r_out, 0
				stb		r6, 2(r4)
		
			; digit 2 to ascii
			addi	r4, r_buf, 0
			lbz		r6, 0(r4)
			andi.	r6, r6, 0x000F
			cmpi	cr7, r6, 10
			blt		cr7, _digit2
			addi	r6, r6, 39
			_digit2:
				addi	r6, r6, 48
				addi	r4, r_out, 0
				stb		r6, 3(r4)
			
			; print
			li		r0, 4
			li		r3, 1
			addi	r4, r_out, 0
			li		r5, 5
			sc
			nop
	
			b _loop
	
		_finish:
			li		r0, 4
			li		r3, 1
			addi	r4, r_end, 0
			li		r5, 1
			sc
			nop
			
		blr