; stdlib.h -- Standard interface definitons for the Hawk monitor.
; language:   SMAL32 assembly language, intended as an include file
; author:     Douglas W. Jones
; date:       Dec 1, 2019

;   Linkage conventions:
;     R1 -- used for return address linkage by all support routines.
;     R2 -- available for use as an activation record pointer.
;     R3 -- typically the first parameter and function return value
;     R4 -- typically the second parameter, if there is one.

;-------------------------------
; the one universal monitor service

	EXT	EXIT  	; terminate application (same as return from main)
		 	;   touches nothing, all registers can be inspected
                        ; C equivalent: exit(status)

;-------------------------------
; arithmetic routines

	EXT	TIMES	; multiply two signed integers
	EXT	TIMESU	; multiply two unsigned integers
			;   takes R3=multiplicand R4=multiplier
			;   returns R3=product
			;   wipes out R4-R6
                        ; C equivalent: product = multiplier * multiplicand

	EXT	DIVIDEU	; divide two unsigned integers
			;   takes R3=dividend R4=divisor
			;   returns R3=quotient R4=remainder
			;   wipes out R5-R6
                        ; C equivalent: quotient  = dividend / divisor
                        ;               remainder = dividend % divisor

	EXT	RAND	; pseudo-random number generator
			;   returns R3=e, next element in pseudo-random stream
			;   note 0 <= e <= RAND_MAX   
			;   wipes out R4-R6
                        ; C equivalent: e = rand()

RAND_MAX=	32767

;-------------------------------
; heap management

	EXT	MALLOC	; allocate memory on the heap
			;   takes R3=size of desired memory region in bytes
			;   returns R3=pointer to a block of memory or NULL
			;   note NULL is returned when no memory is available
			;        if not null, the block will be word aligned
			;        and it will be big enouth to hold size bytes
			;   wipes out R4-R7
                        ; C equivalent: block = malloc(size)

	EXT	FREE	; return unneeded memory to the heap
			;   takes R3=pointer to a memory block
			;   note that R3 must point to a block previously
			;        returned by malloc and not previously freed
			;   wipes out R4
                        ; C equivalent: free(block)

NULL	=	0	; duplicates definition in stdio.h