/*******************************************************
*         File:	 one2N.s
*         Date:	 Sep 29, 2021
*       Author:  DSS
*    Assembler:  as under the gcc compiler                 
*      Purpose:	 print integers 1 thru a user-provided value N
*******************************************************/
	
.globl main

main:
	push 	%rbp           	# keep stack aligned
	#Get how many to print from user
	mov  	$0, %rax       	# clear AL (zero FP args in XMM registers)
	leaq 	prompt(%rip), %rdi  	
				# load format string to proper register
	call    printf          # print it
	# Read int
	leaq 	fmt_in(%rip), %rdi  	
				# load format string
	leaq 	nums(%rip), %rsi  	
				# set storage to address of x
	call	scanf

	/* Uncomment to echo value read; must uncomment res: below
	xor     %rax, %rax      # Another way to 0 out %rax; 
	leaq 	res(%rip), %rdi # load format string
	movq 	nums(%rip), %rsi#  must load value from memory!!
        movq	%rsi, %r14
	call	printf
	*/
	
 	# Load value from memory
	movq 	nums(%rip), %rsi
        movq	%rsi, %r14

	# Load value to print to unused register
	# Originally used %r10 for value but it got clobbered
	mov	$0, %r12	#put value in reg r12
loop:	
	inc	%r12      	#inc value
	# printf(format,nextValue); 
	# Put format string in %rdi, variable corresponding to %d in 01
	# then call printf function
        mov     $format, %rdi
	mov	%r12,%rsi	#put value in %rsi for output 
        xor     %rax, %rax      #must 0 out %rax 
	call	printf		#print it
	cmp	%r14w,%r12w	#compare counter with numInts; just lowest word (why?)
	jl	loop		#if reg values were unequal (ctr#=numInts), iterate
done:	
	pop 	%rbp
	ret

.data
format: .asciz	"%d\n"
fmt_in: .string "%d"
prompt: .asciz	"Print values ending with? >" 
nums:	.long 0
# res:	.string "Read:%d\n"  Uncomment with echo value code above