Print register works.

swi-util.S

@@ -1,68 +1,86 @@
 .global log
-/* Address of string to log in R1. */
 log:
-mov     x29, x30
-mov     w4, w1
+# Address of string to log is in R1.
+	mov	x29, x30
+	mov	w25, w1
 
-#ldr     x1, =elap    
-#mov     w0, #0x30    /* SWI: elapsed  */
-#hlt     #0xf000      /* R1 = &elap */
+	ldr	x1, =elap	
+	mov	w0, #0x30	/* elapsed instructions */
+	hlt	#0xf000
 
-mov     w6, #140
-bl      print_byte
+	ldr	x7, =testdata
+	ldr	w6, [x7]
+	bl	print_quad
+	ldr	w6, [x7, #4]
+	bl	print_quad
 
-ret     x29
-
-print_byte:
-mov     x28, x30
-asr     w1, w6, #4      /* Top four bits.    */
-bl      print_nibble
-and     w1, w6, #15     /* Bottom four bits. */
-bl      print_nibble
-ret x28
-
-print_nibble:
-# R1 is a nibble.
-ldr     x4, =hbyte
-add     w2, w1, #0x30   /* R2 = '0' + w1 */
-add     w3, w1, #0x57   /* R3 = 'a' + w1  - 10 */
-cmp     x1, #9
-csel    w1, w2, w3, ls
-strb    w1, [x4]
-mov     x1, x4
-mov     w0, #0x03
-hlt     #0xf000
-ret
+	# Print the string
+	mov	x1, x25
+	mov	w0, #0x04
+	hlt	#0xf000
 
 
-hex_byte:
-ldr     b6, [x6]
-ldr     x8, =hbyte
+	ret	x29
 
-asr     w1, w6, #4      /* Top four bits. */
-add     w5, w1, #0x30   /* R5 = '0' + w1 */
-add     w7, w1, #0x61   /* R7 = 'a' + w1 */
-cmp     w1, #9
-csel    w1, w5, w7, mi
+.global print_quad
+print_quad:
+# [0 1 2 3 4 6 26 27 28 30]
+	mov	x27, x30
+	rev	w6, w6
+	mov	w26, #0
+	pq_loop:
+	 bl	print_byte
+	 add	w26, w26, #1
+	 cmp	w26, #4
+	 asr	w6, w6, #8
+	 blt	pq_loop
+	ldr	x1, =hbyte
+	mov	x2, #0x7c
+	strb	w2, [x1]
+	mov	x0, #0x03
+	hlt	#0xf000
+	ret	x27
 
-strb    w1, [x8]
-mov     x1, x8
-mov     w0, #0x03
-hlt     #0xf000
+print_r5:
+	mov	x24, x30
+	ret	x24
 
-and     x1, x6, #15
-cmp     w1, #9
-csel    w1, w5, w7, mi
-strb    w1, [x8]
-mov     x1, x8
-mov     w0, #0x03
-hlt     #0xf000
+print_byte:
+# R6 is a byte.
+# [0 1 2 3 4 6 28 30]
+	mov	x28, x30
+	asr	w1, w6, #4      /* Top four bits.    */
+	and	w1, w1, #0x0000000f
+	bl	print_nibble
+	and	w1, w6, #0x0000000f     /* Bottom four bits. */
+	bl	print_nibble
+	ret	x28
 
-ret
+print_nibble:
+# R1 is a nibble.
+# [0 1 2 3 4 30]
+	ldr	x4, =hbyte
+	add	w2, w1, #0x30   /* R2 = '0' + w1 */
+	add	w3, w1, #0x57   /* R3 = 'a' + w1  - 10 */
+	cmp	x1, #9
+	csel	w1, w2, w3, ls
+	strb	w1, [x4]
+	mov	x1, x4
+	mov	w0, #0x03
+	hlt	#0xf000
+	ret
 
 elap:
-  .word 0x00000000
-  .word 0x00000000
+	.word 0x00000000
+	.word 0x00000000
 
 hbyte:
-  .byte 0x00
+	.byte 0x00
+
+.align 8
+testdata:
+	.word 0x01234567
+	.word 0xdeadbeef
+
+newline:
+	.byte '\n'

test-util.S

@@ -1,19 +1,23 @@
 .section .text, "ax"
+
 .global _start
 _start:
-# Attempt to initialize the stack?
-#adr     x1, stack_addr
-#ldr     x1, [x1]
-#mov     sp, x1
+	bl	init_stack
+
+test:	ldr	x1, =hello
+	bl	log
 
-ldr     w1, =hello
-bl      log
-movz    w0, #0x18    /* SWI: Exit     */
-hlt     #0xf000
-b       .            /* Infinite loop */
+exit:	movz	w0, #0x18	/* Exit */
+	hlt	#0xf000
+	b	.
 
-hello:
-  .ascii "\nHello, world!\n"
+init_stack:
+	adr	x29, stack
+	ldr	x29, [x29]
+	mov	sp, x29
+	ret
 
-stack_addr:
-  .quad  0x0000000088000000
+hello:	.ascii "Hello, world!\n\0"
+
+.align 2
+stack:	.quad 0x0000000088000000