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