# Stack Library
#  This'll get a whole lot cleaner when I can tell the
#  depth of the stack automagically

# peek -- return whatever string is on the stack
#   Inputs: the offset on the stack
#  Outputs: the string
# Non-Destructive!
# Does *not* test for bounds conditions
PEEK:   pushi
	restore I0
	set I3, I0
	inc I0
	set I2 0
PLOOP:  ge I2, I3, POL
	rotate_up I0
	inc I2
	branch PLOOP
POL:
	restore S0
	save S0
	eq I0, 0, EOP
	rotate_up I0

EOP:	save S0
	popi
	ret

# REPLACE -- replace thing at stack position X
#   Inputs: the offset to remove
#	    the string to leave in its place
#  Outputs: The string removed
#     Note: Almost *identical* to PEEK above
# Does *not* test for bounds conditions
REPLACE: pushi
	pushs
	restore S1
	restore I0
	set I3, I0
	inc I0
	set I2, 0
RLOOP:	ge I2, I3, ROL
	rotate_up I0
	inc I2
	branch RLOOP
ROL:	restore S0
	save S1
	eq I0, 0, ENDOFREPLACE
	rotate_up I0
ENDOFREPLACE:
	save S0
	popi
	pops
	ret

# swap -- swap the position of two strings on the stack
#  Inputs: Offsets of the two things on the stack
# Outputs: None.
# Does *not* test for bounds conditions
SWAP:	pushi
	pushs

	restore I0
	restore I1
	save I0
	save "-"     # Just a dummy
	bsr REPLACE

	restore S0
	save I1
	save S0

	bsr REPLACE

	restore S1
	save I0
	save S1

	bsr REPLACE
	restore S1   # dummy
        popi
	pops
	ret

# Sort whatever's on the stack.
#   Yes, this is a bubble sort.  Get over it.
#  Inputs:  Stack depth on top of the stack
# Outputs:  Stack depth on top of the stack
SORTSTACK:
	pushi
	pushs
	restore I5
	set I0, 0
	set I1, 0
BUBBLE: inc I1
	le I1, I0, BUB1
	set I1, 0
	inc I0
BUB1:	ge I0, I5, SORTEND
	save I1
	bsr PEEK
	restore S2
	save I0
	bsr PEEK
	restore S3
	le S2, S3, BUBBLE
	save I1
	save I0
	bsr SWAP
	branch BUBBLE

SORTEND:
	save I5
	popi
	pops
	ret