Clean up expression logic, implement local variables
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parent
58a80f982f
commit
4cd52d202e
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@ -23,7 +23,7 @@
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(set self.breakpoints {}))
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(fn Machine.boot [self]
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(when (not self.pid)
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(set self.pid (start-mame :apple2e))))
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(set self.pid (start-mame :apple2gs))))
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(fn Machine.run [self]
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(self:boot)
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(self:connect))
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128
ssc/init.fnl
128
ssc/init.fnl
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@ -8,12 +8,13 @@
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; * All values are 16-bit integers, like Forth or BCPL.
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; * Data and return addresses are mixed on one stack, unlike Forth.
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; * Function calls take a fixed number of arguments, and return 0 or 1 results. The compiler enforces arity checking.
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; * To call a function taking arguments [arg1 arg2 arg3], arg3 should be in the A register, and the stack should look like:
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; arg1 arg2 return-address
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; * The caller is responsible for removing arg1 + arg2 from the stack once the function returns.
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; * The caller is responsible for preserving the X and Y registers, if this is desirable.
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; * To call a function taking arguments [arg1 arg2 arg3], all 3 arguments should be pushed to the stack before calling.
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; When the function takes control, the stack should look like this:
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; arg1 arg2 arg3 return-address
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; * The caller is responsible for removing all arguments from the stack once the function returns.
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; * The caller is responsible for preserving the A, X and Y registers, if this is desirable.
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; * If the function returns a value, it is stored in the A register.
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; * If a function takes no arguments and returns no result, it is not obliged to preserve the A register.
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; * If a function returns no result, it is not obliged to preserve the A register.
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; * Multitasking is achieved by overlapping the D and S registers on the same 256-byte page of memory.
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; Yielding to a new task involves saving the S register, setting the D register to the new task's page,
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; then setting the S register to the saved value in the old task.
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@ -28,6 +29,11 @@
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; Compiler notes:
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; Expressions are of the form [:function arg1 arg2 arg3]
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; args are either strings (symbols) or numbers
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; TODO:
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; * implement read / write (pointers)
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; * implement functions
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; * implement custom special forms (macros?)
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(local Object (require :core.object))
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(local lume (require :lib.lume))
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(local Ssc (Object:extend))
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@ -36,53 +42,87 @@
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(fn Ssc.new [self ?opts]
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(local opts (or ?opts {}))
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(set self.prg (or opts.prg (Prg.new nil :65816)))
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(when opts.exprforms (set self.exprforms opts.exprforms))
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(when opts.stmtforms (set self.stmtforms opts.stmtforms))
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(set self.functions {}))
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(set self.forms (lume.clone (or opts.forms self.__index.forms)))
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(set self.functions {})
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(set self.locals []))
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(fn Ssc.push [self ?local]
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(table.insert self.locals (or ?local [:tmp]))
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[:pha])
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(fn Ssc.drop [self ?local]
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(match (. self.locals (length self.locals))
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[:tmp] (when (not= ?local nil) (error (.. "Internal stack error: expected " ?local ", got temporary")))
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loc (when (not= ?local loc) (error (.. "Internal stack error: expected " (or ?local "temporary") " temporary, got " loc))))
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(tset self.locals (length self.locals) nil)
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[:ply])
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(set Ssc.exprforms
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{:+ (lambda [self first ...]
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(local block [:block [:clc] (self:compile-expr first)])
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(for [i 1 (select :# ...)]
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(let [val (select i ...)]
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(table.insert block
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(match val
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1 [:inc]
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-1 [:dec]
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(where val (= (type val) :number)) [:adc val]
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_ [:block (self:compile-expr val) [:adc 0 :s] [:ply]]))))
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block)
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:- (lambda [self first ...]
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(local block [:block [:sec] (self:compile-expr first)])
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(for [i 1 (select :# ...)]
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(let [val (select i ...)]
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(table.insert block
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(match val
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1 [:dec]
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-1 [:inc]
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(where val (= (type val) :number)) [:sbc val]
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_ [:block (self:compile-expr val) [:sbc 0 :s] [:ply]]))))
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block)
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:asm (lambda [self ...] [:block ...])
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})
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(fn countiter [minmax ?max]
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(let [min (if ?max minmax 1)
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max (or ?max minmax)]
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(values (fn [_ i] (if (>= i max) nil (+ i 1)))
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nil
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min)))
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(fn [_ iprev]
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(let [i (if iprev (+ iprev 1) min)]
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(when (<= i max) i)))))
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(fn pairoff [l]
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(fn [_ iprev] (let [i (if iprev (+ iprev 2) 1)]
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(when (< i (length l)) (values i (. l i) (. l (+ i 1)))))))
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(set Ssc.forms
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{:asm (fn [self ...] [:block ...])
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:do (fn [self ...] (lume.concat [:block] (icollect [i (countiter (select :# ...))] (self:compile-expr (select i ...)))))
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:let (fn [self bindings ...]
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(lume.concat [:block]
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(icollect [_ symbol expr (pairoff bindings)]
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[:block (self:compile-expr expr) (self:push symbol)])
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[(self:compile-expr [:do ...])]
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(icollect [i-half (countiter (/ (length bindings) 2))]
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(self:drop (. bindings (- (length bindings) (* i-half 2) -1))))))
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:+ (lambda [self first ...]
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(local block [:block (self:compile-expr first)])
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(for [i 1 (select :# ...)]
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(let [val (select i ...)]
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(table.insert block
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(match val
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1 [:inc] 2 [:block [:inc] [:inc]]
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-1 [:dec] -2 [:block [:dec] [:dec]]
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(where val (= (type val) :number)) [:block [:clc] [:adc val]]
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(where sym (= (type sym) :string) (self:local-offset sym)) [:block [:clc] [:adc (self:local-offset sym) :s]]
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_ [:block (self:push) (self:compile-expr val) [:clc] [:adc 0 :s] (self:drop)]))))
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block)
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:- (lambda [self first ...]
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(let [block [:block (self:compile-expr first)]
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nargs (select :# ...)]
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(if (= nargs 0) (table.insert block [:block [:eor 0xffff] [:inc]]) ; negate with two's complement
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(for [i 1 nargs]
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(let [val (select i ...)]
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(table.insert block
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(match val
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1 [:dec] 2 [:block [:dec] [:dec]]
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-1 [:inc] -2 [:block [:inc] [:inc]]
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(where val (= (type val) :number)) [:block [:sec] [:sbc val]]
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(where sym (= (type sym) :string) (self:local-offset sym)) [:block [:sec] [:sbc (self:local-offset sym) :s]]
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_ [:block (self:push) (self:compile-expr val) [:sec] [:sbc 0 :s] (self:drop)])))))
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block))
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})
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(fn Ssc.local-offset [self symbol]
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(var offset nil)
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(for [i 1 (length self.locals)]
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(when (= (. self.locals i) symbol)
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(set offset (* 2 (- (length self.locals) i)))))
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offset)
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(fn Ssc.compile-expr [self expr]
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(match expr
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(where num (= (type num) :number)) [:block [:pha] [:lda num]]
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;:string TODO: oh shit I need to keep track of local scoping etc
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(where [func & args] (= (?. self.functions func :arity) (length args))
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(. self.functions func :returns-value))
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(let [pre (icollect [_ arg (ipairs args)] (self:compile-expr arg))
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post (if (<= (length args) 1) [] (icollect [_ (countiter (- (length args) 1))] [:ply]))]
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(where num (= (type num) :number)) [:lda num]
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(where loc (= (type loc) :string) (self:local-offset loc)) [:lda (self:local-offset loc) :s]
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; TODO: Global scope
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(where [func & args] (= (?. self.functions func :arity) (length args)))
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(let [pre (icollect [_ arg (ipairs args)] [:block (self:compile-expr arg) (self:push)])
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post (icollect [_ (countiter (length args))] (self:drop))]
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(lume.concat [:block] pre [[:jsr func]] post))
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(where [form & args] (. self.exprforms form))
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((. self.exprforms form) self (table.unpack args))
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(where [form & args] (. self.forms form))
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((. self.forms form) self (table.unpack args))
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_ (error (.. "Unrecognized expression " (fv expr)))))
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Ssc
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