.include "lib.s"

.macro bufpush
	cmpq $bufend, %rdi
	jle 9f
	stosb
	9:
.endm

.globl printf
printf:
	prologue

	backup %rax, %rbx, %rcx, %rdx
	backup %rsi, %rdi

	movq 16(%rbp), %rsi
	leaq 24(%rbp), %rbx
	movq $buf, %rdi

.loop:
	lodsb
	testb %al, %al
	jz .loopout

	cmpb $'%, %al
	jne .append

	lodsb
	testb %al, %al
	jz .loopout

	cmpb $'%, %al
	je .append

	cmpb $'s, %al
	je .print_string

	cmpb $'d, %al
	je .print_signed

	cmpb $'u, %al
	je .print_unsigned

	jmp .loop

.append:
	bufpush
	jmp .loop

.print_string:
	backup %rsi

	movq (%rbx), %rsi
	addq $8, %rbx
	jmp 2f

	1: bufpush 
	2: lodsb
	testb %al, %al
	jnz 1b

	restore %rsi
	jmp .loop

.print_signed:
	movq (%rbx), %rax
	addq $8, %rbx

	cmpq $0, %rax
	jge 1f

	pushq %rax
	movb $'-, %al
	bufpush
	popq %rax
	negq %rax

	1:
	movq $10, %rcx
	call .print_number
	jmp .loop

.print_unsigned:
	movq (%rbx), %rax
	addq $8, %rbx

	movq $10, %rcx
	call .print_number
	jmp .loop

.print_number:
	xorq %rdx, %rdx
	divq %rcx
	pushq %rdx
	testq %rax, %rax
	jz 1f
	call .print_number
	1:
	popq %rax
	addq $'0, %rax
	bufpush
	ret

.loopout:
	movq %rdi, %rdx
	subq $buf, %rdx
	movq $buf, %rsi
	movq $STDOUT, %rdi
	sys write

	restore %rsi, %rdi
	restore %rax, %rbx, %rcx, %rdx

	leave
	ret

.bss
.comm buf, 4096
.comm bufend, 2