fn evaluate defs: (addr handle function), bindings: (addr table), scratch: (addr line), end: (addr word), out: (addr int-stack) {
var line/eax: (addr line) <- copy scratch
var word-ah/eax: (addr handle word) <- get line, data
var curr/eax: (addr word) <- lookup *word-ah
var curr-text-storage: (stream byte 0x10)
var curr-text/edi: (addr stream byte) <- address curr-text-storage
clear-int-stack out
$evaluate:loop: {
# precondition (should never hit)
compare curr, 0
break-if-=
# update curr-text
emit-word curr, curr-text
#? print-stream-to-real-screen curr-text
#? print-string-to-real-screen "\n"
$evaluate:process-word: {
# if curr-text is an operator, perform it
{
var is-add?/eax: boolean <- stream-data-equal? curr-text, "+"
compare is-add?, 0
break-if-=
var _b/eax: int <- pop-int-stack out
var b/edx: int <- copy _b
var a/eax: int <- pop-int-stack out
a <- add b
push-int-stack out, a
break $evaluate:process-word
}
{
var is-sub?/eax: boolean <- stream-data-equal? curr-text, "-"
compare is-sub?, 0
break-if-=
var _b/eax: int <- pop-int-stack out
var b/edx: int <- copy _b
var a/eax: int <- pop-int-stack out
a <- subtract b
push-int-stack out, a
break $evaluate:process-word
}
{
var is-mul?/eax: boolean <- stream-data-equal? curr-text, "*"
compare is-mul?, 0
break-if-=
var _b/eax: int <- pop-int-stack out
var b/edx: int <- copy _b
var a/eax: int <- pop-int-stack out
a <- multiply b
push-int-stack out, a
break $evaluate:process-word
}
# if curr-text is a known function name, call it appropriately
{
var callee-h: (handle function)
var callee-ah/eax: (addr handle function) <- address callee-h
find-function defs, curr-text, callee-ah
var callee/eax: (addr function) <- lookup *callee-ah
compare callee, 0
break-if-=
perform-call callee, out, defs
break $evaluate:process-word
}
# otherwise it's an int
{
var n/eax: int <- parse-decimal-int-from-stream curr-text
push-int-stack out, n
}
}
# termination check
compare curr, end
break-if-=
# update
var next-word-ah/edx: (addr handle word) <- get curr, next
curr <- lookup *next-word-ah
#
loop
}
}
fn find-function first: (addr handle function), name: (addr stream byte), out: (addr handle function) {
var curr/esi: (addr handle function) <- copy first
$find-function:loop: {
var _f/eax: (addr function) <- lookup *curr
var f/ecx: (addr function) <- copy _f
compare f, 0
break-if-=
var curr-name-ah/eax: (addr handle array byte) <- get f, name
var curr-name/eax: (addr array byte) <- lookup *curr-name-ah
var done?/eax: boolean <- stream-data-equal? name, curr-name
compare done?, 0 # false
{
break-if-=
copy-handle *curr, out
break $find-function:loop
}
curr <- get f, next
loop
}
}
fn perform-call _callee: (addr function), caller-stack: (addr int-stack), defs: (addr handle function) {
var callee/ecx: (addr function) <- copy _callee
# create bindings for args
var table-storage: table
var table/esi: (addr table) <- address table-storage
initialize-table table
#
var curr-arg-ah/eax: (addr handle word) <- get callee, args
var curr-arg/eax: (addr word) <- lookup *curr-arg-ah
#
var curr-key-storage: (handle array byte)
var curr-key/edx: (addr handle array byte) <- address curr-key-storage
{
compare curr-arg, 0
break-if-=
# create binding
word-to-string curr-arg, curr-key
{
var curr-val/eax: int <- pop-int-stack caller-stack
bind-int-in-table table, curr-key, curr-val
}
#
var next-arg-ah/edx: (addr handle word) <- get curr-arg, next
curr-arg <- lookup *next-arg-ah
loop
}
# obtain body
var body-ah/eax: (addr handle line) <- get callee, body
var body/eax: (addr line) <- lookup *body-ah
# perform call
var stack-storage: int-stack
var stack/edi: (addr int-stack) <- address stack-storage
initialize-int-stack stack, 0x10
#? print-string-to-real-screen "about to enter recursive eval\n"
evaluate defs, table, body, 0, stack
#? print-string-to-real-screen "exited recursive eval\n"
# stitch result from stack into caller
var result/eax: int <- pop-int-stack stack
push-int-stack caller-stack, result
}
# Copy of 'simplify' that just tracks the maximum stack depth needed
# Doesn't actually need to simulate the stack, since every word has a predictable effect.
fn max-stack-depth first-word: (addr word), final-word: (addr word) -> result/edi: int {
var curr-word/eax: (addr word) <- copy first-word
var curr-depth/ecx: int <- copy 0
result <- copy 0
$max-stack-depth:loop: {
$max-stack-depth:process-word: {
# handle operators
{
var is-add?/eax: boolean <- word-equal? curr-word, "+"
compare is-add?, 0
break-if-=
curr-depth <- decrement
break $max-stack-depth:process-word
}
{
var is-sub?/eax: boolean <- word-equal? curr-word, "-"
compare is-sub?, 0
break-if-=
curr-depth <- decrement
break $max-stack-depth:process-word
}
{
var is-mul?/eax: boolean <- word-equal? curr-word, "*"
compare is-mul?, 0
break-if-=
curr-depth <- decrement
break $max-stack-depth:process-word
}
# otherwise it's an int (do we need error-checking?)
curr-depth <- increment
# update max depth if necessary
{
compare curr-depth, result
break-if-<=
result <- copy curr-depth
}
}
# if curr-word == final-word break
compare curr-word, final-word
break-if-=
# curr-word = curr-word->next
var next-word-ah/edx: (addr handle word) <- get curr-word, next
curr-word <- lookup *next-word-ah
#
loop
}
}