uskel/include/apply.s

.include "include/data.s"

# | fun | arg[1] | arg[2] | ... | arg[args-1] | -> cont
.thunkcode apply
	#determine how much stuff we need
	mov 010(%rbp), %rcx
	dec %rcx # we don't move the FUN
	lea 040(,%rcx,010), %rbx # all args (in rcx) + rbp+rsi + 2qw thunk header
	needs_alloc %rbx

	# push all closure args
	mov %rcx, %rbx # backup arg count
	lea 030(%rbp, %rcx, 010), %rdx #point behind the thunk (this re-adds the FUN qw!)
	apply_copy:
	sub $010, %rdx
	pushq (%rdx)
	loop apply_copy

	# push thunk header (+2 args for rbp/rsi) and continue evaluating the FUN
	add $2, %rbx
	thunkto %rsi, $apply_fini, %rbx, %rbp, %rsi
	blackhole
	enter 020(%rbp)

# fun -> | ret (with args) | cont |
.thunkcode apply_fini
	mov (%rsi), %r9 # infotable for the original function
	mov 020(%rbp), %r10 # the original thunk
	mov 020(%rsi), %r11 # amount of args applied in the closure
	mov -010(%r9), %r12 # amount of args required to make a thunk
	mov 010(%rbp), %r13 # amount of args in the original thunk
	sub $2, %r13 # amount of args we want to apply (the extra ones are the backup rbp, rsi, and the FUN)

	lea (%r11, %r13), %r14 # total amount arguments we have
	lea 050(%r14), %r15 # how much memory this needs in extreme #TODO: check this
	needs_alloc %r15
	# worst-case memory is: we make a thunk (2 headers + some args) and a
	# leftover closure (3 headers + rest of args)

	# Now that we have enough memory, do we have enough arguments to do anything?
	cmp %r12, %r14
	ja apply_fini_o

apply_fini_pt:
	# Not enough args or exactly enough args.
	# Basically make a function or a thunk that is almost the same.

	# first move thunk params
	mov %r13, %rcx
	cmp $0, %rcx
	jz apply_fini_pt_thunk_skip
	lea 040(%rbp, %r13, 010), %rdx
	apply_fini_pt_thunk_copy:
	sub $010, %rdx
	pushq (%rdx)
	loop apply_fini_pt_thunk_copy
	apply_fini_pt_thunk_skip:

	# now move the fun params
	mov %r11, %rcx
	cmp $0, %rcx
	jz apply_fini_pt_fun_skip
	lea 030(%rsi, %r11, 010), %rdx
	apply_fini_pt_fun_copy:
	sub $010, %rdx
	pushq (%rdx)
	loop apply_fini_pt_fun_copy
	apply_fini_pt_fun_skip:

	# make a thunk
	thunk 010(%rsi), %r14 # thunk code (from FUN code) + amount of args
	cmp %r12, %r14 # are we precisely at the right amount of arguments for a thunk?
	jb apply_fini_pt_closure # if not, wrap a closure

	apply_fini_pt_thunk:
	# we've made the exact thunk we want. Replace the original with an indirect
	mov %rsp, 010(%r10)
	movq $IND_code, (%r10)
	# and tell the new thunk to evaluate into the original continuation
	mov 030(%rbp), %rsi
	enter %rsp

	apply_fini_pt_closure:
	# if we still have an incomplete closure, rewrap it in the original FUN wrappage
	thunkto %rsi, %r9
	# replace the original thunk with an indirect
	mov %rsp, 010(%r10)
	movq $IND_code, (%r10)
	# and return the closure (%rsi) to the original continuation as a result
	enter 030(%rbp)

apply_fini_o: #TODO needs to be tested
	# too many args, we need to split off a bit
	# first move just the right amount of args off the thunk
	mov %r12, %rcx
	sub %r11, %rcx
	cmp $0, %rcx
	jz apply_fini_o_tc_skip
	lea 040(%rbp, %rcx, 010), %rdx
	apply_fini_o_tc_copy:
	sub $010, %rdx
	pushq (%rdx)
	loop apply_fini_o_tc_copy
	apply_fini_o_tc_skip:

	# now add all the args from the closure
	mov %r11, %rcx
	cmp $0, %rcx
	jz apply_fini_o_fun_skip
	lea 030(%rsi, %r11, 010), %rdx
	apply_fini_o_fun_copy:
	sub $010, %rdx
	pushq (%rdx)
	loop apply_fini_o_fun_copy
	apply_fini_o_fun_skip:

	# make a thunk out of the successfully finished closure; it will be
	# evaluated later
	thunkto %r15, 010(%rsi), %r14

	# now make a thunk with the rest of the stuff
	mov %r14, %rcx
	sub %r12, %rcx
	mov %rcx, %r14 # backup the leftover-args count for later
	cmp $0, %rcx
	jz apply_fini_o_tt_skip
	lea 040(%rbp, %r13, 010), %rdx
	apply_fini_o_tt_copy:
	sub $010, %rdx
	pushq (%rdx)
	loop apply_fini_o_tt_copy
	apply_fini_o_tt_skip:

	# finish the leftovers thunk
	add $1, %r14 # (1 FUN to apply to + lefrover args)
	thunk $apply, %r14, %r15 # push the 1st arg (FUN) + argcount

	# replace the original thunk with an indirect
	mov %rsp, 010(%r10)
	movq $IND_code, (%r10)
	# return the applied function to the original continuation
	mov 030(%rbp), %rsi
	enter %rsp