; exnl6.asm  example  declare and call funstions and procedures
	extern printf

	section .data		; Data section, initialized variables
msg:	db "nasm  exnl6.asm running", 0	; C string needs 0
msg2:	db "exnl6.asm finished", 0	
fmt:    db "%s", 10, 0
fmti	db "diff = %d", 10, 0	
fmtf:	db "ssq = %f", 10, 0	
af:	dq 1.1
bf:	dq 3.3
ai:	dq 13
bi:	dq 27

	section .bss		; variable and array section
cf:	resq	1
ci:	resq	1
tmp:	resq	1
	
        section .text           ; Code section.
        global main
main:
        push    rbp		; set up stack frame, must be aligned
	
	mov	rdi,fmt         ; address of format, required register rdi
	mov	rsi,msg         ; address of data
	mov	rax,0		; or can be  xor  rax,rax
        call    printf		; Call C function

	call	jprt		; call no parameter procedure

	mov	rdi,[ai]	; first integer parameter value
	mov	rsi,[bi]	; second integer paramenter value
	call	diff		; function return in rax
	mov	[tmp],rax	; save result and print result using macro
;	print
	mov     rdi, fmti  ; address of format string
	mov     rsi, [tmp] ; int value
	mov     rax, 0	   ; 0 floating point arguments to printf
	call    printf	   ; Call C function
	
	movq	xmm0, qword[af]  ; first double parameter value
	movq	xmm1, qword[bf]  ; second double parameter value
	call	ssq		 ; function return in xmm2
	movq 	qword[tmp], xmm2 ; save result and print result
;	print
	mov     rdi, fmtf        ; address of format string
	movq    xmm0, qword[tmp] ; first floating point in fmt
	mov     rax, 1	         ; 1 floating point arguments to printf
	call    printf	         ; Call C function
	
	mov	rdi,fmt
	mov	rsi,msg2
	mov	rax,0
	call	printf
        pop     rbp		; restore stack 
	mov	rax,0		; normal, no error, return value
	ret			; return

	;  function definitions, called above
        section .data		; Data section
jprthi:	db "Hi from jprt", 10, 0
	
	section .bss		; variables, arrays space
tmpf:	resq	1		; temp space
parf1:	resq	1
parf2:	resq 	1
	
	section .text           ; Code section.
jprt:	mov	rdi,fmt		; no parameters
	mov	rsi,jprthi
	mov	rax,0
	call	printf
	ret			; end jprt

diff:	mov	rax,rdi		; rdi first integer parameter
	sub	rax,rsi		; rsi second integer parameter
	ret			; function result in rax


ssq:	movq	qword[parf1], xmm0 ; save first parameter
	movq	qword[parf1], xmm1 ; save second parameter
	fld	qword[parf1]	   ; first parameter
	fmul	qword[parf1]	   ; squared
	fstp	qword[tmpf]	   ; saved
	fld	qword[parf2]	   ; second parameter
	fmul	qword[parf1]	   ; squared
	fadd	qword[tmpf]	   ; sum
	fstp	qword[tmpf]	   ; return value
	movq	xmm2, qword[tmpf]  ; return in register
	ret