; pb3_test.psm
; A very simple kcasm test for PacoBlaze3
; We load some data to registers and do some loops while
; one register is modified when an interrupt occurs

; register definitions
register r0, 0 ; alias register #0 (s0) as r0
register r1, 1 ; alias register #1 (s1) as r1
register ic, 15 ; counter register used by our interrupt service routine (isr)

; constant definitions
constant binary, %1001 ; a binary value
constant octal, @77 ; an octal value
constant decimal, &123 ; a decimal value
constant hexadecimal, $ca ; an hexadecimal value
constant character, 'a' ; a character value

; our entry point
start:
	load r0, binary ; load r0 with the 'binary' value
	load r1, $fe ; load r1 with $fe in hex
	load ic, 0 ; set up the initial value of the interrupt counter register

	load s2, 0 ; clear register #2
	add s2, r0 ; add register #0 to register #2
	addcy s2, r1 ; add with carry register #1 to register #2

	interrupt enable ; enable interrupt

; our first loop
loop:
_loop: ; 'loop' alias, same program counter
	input s3, s2 ; read into register #3 with port value at id in register #2
	subcy s3, 1 ; substract 1 with carry
	output s3, s2 ; write back register #3 value
	jump c, loop_1 ; jump if carry to 'loop_1'
	srx s2 ; shift-right extended register #2

loop_1: slx s3 ; shift-left extended register #3
	call func ; call function 'func'
	jump loop ; inconditional jump back to 'loop'

func: ; a function
	add s0, hexadecimal ; add 'hexadecimal' value to register #0
	subcy s0, decimal ; substract with carry 'decimal' to register #0
	return ; return back

; our interrupt service routine
isr:
	add ic, 1 ; increment register ic (#15)
	returni enable ; return from interrupt with interrupts enabled

int:	address $3ff ; the interrupt entry point
	jump isr ; jump to 'isr'