sysspim.s

# system calls for Tiger, when running on SPIM
#
# $Id: sysspim.s,v 1.1 2002/08/25 05:06:41 shivers Exp $

	.globl malloc
	.ent malloc
	.text
malloc:
	# round up the requested amount to a multiple of 4
	add $a0, $a0, 3
	srl $a0, $a0, 2
	sll $a0, $a0, 2

	# allocate the memory with sbrk()
	li $v0, 9
	syscall
	
	j $ra

	.end malloc



	.data
	.align 4
getchar_buf:	.byte 0, 0


getchar:
	# read the character
	la $a0, getchar_buf
	li $a1, 2
	li $v0, 8
	syscall

	# return it
	lb $v0, ($a0)
	j $ra
	

	.data
	.align 4
putchar_buf:	.byte 0, 0

	.text
putchar:
	# save the character so that it is NUL-terminated 
	la $t0, putchar_buf
	sb $a0, ($t0)

	# print it out
	la $a0, putchar_buf
	li $v0, 4
	syscall

	j $ra


	.text	
# just prints the format string, not the arguments
printf:
	li $v0, 4
	syscall
	j $ra



	.text 
# CUSTOM FUNCTION: prints an integer found in $a0 
putint:
	li $v0, 1
	syscall
	j $ra


	.text
exit:
	li $v0, 10
	syscall