250 lines
8.3 KiB
Fennel
250 lines
8.3 KiB
Fennel
(local {: stream : kvstream : one} (require "stream"))
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(local opcodes {})
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; op mode arg
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; single-byte ops
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(let [ops
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{:php 0x08 :plp 0x28 :pha 0x48 :pla 0x68 :dey 0x88 :tay 0xa8 :iny 0xc8 :inx 0xe8
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:clc 0x18 :sec 0x38 :cli 0x58 :sei 0x78 :tya 0x98 :clv 0xb8 :cld 0xd8 :sed 0xf8
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:txa 0x8a :txs 0x9a :tax 0xaa :tsx 0xba :dex 0xca :nop 0xea :brk 0x00 :rti 0x40
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:rts 0x60}]
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(each [opcode byte (pairs ops)]
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(tset opcodes opcode (fn [mode] (if mode nil byte)))))
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; branch ops
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(let [ops {:bpl 0x10 :bmi 0x30 :bvc 0x50 :bvs 0x70 :bcc 0x90 :bcs 0xb0 :bne 0xd0 :beq 0xf0}]
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(each [opcode byte (pairs ops)]
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(tset opcodes opcode (fn [mode] (if (= mode :rel) byte nil)))))
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(set opcodes.jsr (fn [mode] (if (= mode :abs) 0x20 nil)))
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; aaabbbcc ops
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(fn aaabbbcc [aaa cc modemap]
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(local base (bit.bor cc (bit.lshift aaa 5)))
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(fn [mode]
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(local bbb (. modemap mode))
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(if bbb (bit.bor base (bit.lshift bbb 2)) nil)))
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(fn indexed-modes [...]
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(let [modemap {}]
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(each [index mode (pairs [...])]
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(tset modemap mode (- index 1)))
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modemap))
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(fn without-modes [modemap ...]
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(let [newmodemap (table.clone modemap)]
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(each [_ mode (pairs [...])]
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(tset newmodemap mode nil))
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newmodemap))
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(fn only-modes [modemap ...]
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(let [newmodemap {}]
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(each [_ mode (pairs [...])]
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(tset newmodemap mode (. modemap mode)))
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newmodemap))
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; cc=1 ops
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(let [cc1-modes (indexed-modes :zp-x* :zp :imm :abs :zp*-y :zp-x :abs-y :abs-x)
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ops {:ora 0 :and 1 :eor 2 :adc 3 :lda 5 :cmp 6 :sbc 7}]
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(each [opcode aaa (pairs ops)]
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(tset opcodes opcode (aaabbbcc aaa 1 cc1-modes))
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(tset opcodes :sta (aaabbbcc 4 1 (without-modes cc1-modes :imm)))))
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; cc=2 ops
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(let [cc2-modes (indexed-modes nil :zp :a :abs nil :zp-x nil :abs-x)]
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(each [opcode aaa (pairs {:asl 0 :rol 1 :lsr 2 :ror 3})]
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(tset opcodes opcode (aaabbbcc aaa 2 cc2-modes))
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(each [opcode aaa (pairs {:dec 6 :inc 7})]
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(tset opcodes opcode (aaabbbcc aaa 2 (without-modes cc2-modes :a))))))
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(tset opcodes :stx (aaabbbcc 4 2 (indexed-modes nil :zp nil :abs nil nil :zp-y)))
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(tset opcodes :ldx (aaabbbcc 5 2 (indexed-modes :imm :zp nil :abs nil nil :zp-y nil :abs-y)))
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; cc=0 ops
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(let [cc0-modes (indexed-modes :imm :zp nil :abs nil :zp-x nil :abs-x)]
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(tset opcodes :bit (aaabbbcc 1 0 (only-modes cc0-modes :zp :abs)))
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(tset opcodes :sty (aaabbbcc 4 0 (only-modes cc0-modes :zp :abs :zp-x)))
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(tset opcodes :ldy (aaabbbcc 5 0 cc0-modes))
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(each [opcode aaa (pairs {:cpy 6 :cpx 7})]
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(tset opcodes opcode (aaabbbcc aaa 0 (only-modes cc0-modes :imm :zp :abs)))))
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(tset opcodes :jmp (fn [mode] (match mode :abs 0x4c :abs* 0x6c _ nil)))
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(fn size [mode]
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(if
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(or (= mode nil) (= mode :a)) 1
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(= (mode:sub 1 3) :abs) 3
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2))
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(fn opsize [op] (if (= op.opcode :block) 0 (size op.mode)))
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(fn parse-mode-arg [op]
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(match op
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[_ :a] [:a nil]
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([_ imm] ? (= (type imm) "number")) [:imm imm]
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([op addr] ? (and (= (type addr) "string") (= (op:sub 1 1) "b"))) [:rel addr] ; branch
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([_ addr] ? (= (type addr) "string")) [:addr addr]
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[_ addr :x] [:addr-x addr]
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[_ addr :y] [:addr-y addr]
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[_ [addr] :y] [:zp*-y addr]
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[_ [addr :x]] [:zp-x* addr]
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[_ [addr]] [:abs* addr]
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[_] [nil nil]
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_ (error (.. "Unrecognized syntax" (fv op)))))
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(fn parse-ops [block ops]
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(var index 1)
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(each [_ op (ipairs ops)]
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(if (= (type op) "string")
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(tset block.symbols op index)
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(let [opcode (. op 1)]
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(if
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(. opcodes opcode)
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(let [[mode arg] (parse-mode-arg op)]
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(table.insert block.code {: opcode : mode : arg}))
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(= opcode :block)
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(let [ops (table.clone op)]
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(table.remove ops 1)
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(table.insert block.code (parse-ops {: opcode :code [] :symbols {}} ops)))
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(error (.. "Unrecognized opcode " (fv opcode))))
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(set index (+ index 1)))))
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block)
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(fn block [org ...] (parse-ops {:type :code : org :code [] :symbols {}} [...]))
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(fn db [org init] {:type :var : org : init :size 1})
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(fn dw [org init] {:type :var : org : init :size 2})
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(fn allot [org size] {:type :var : org : size})
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(fn make-env [blocks]
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{: blocks
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:push (fn [self block]
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(make-env
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(-> (stream self.blocks)
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(: :concat (one block))
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(: :tolist))))
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:lookup
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(fn [self name]
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(-> (stream self.blocks)
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(: :reverse)
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(: :map
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(fn [block]
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(let [symbol (. block.symbols name)]
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(match (type symbol)
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"number" (. block.code symbol)
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"table" symbol
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_ nil))))
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(: :filter (fn [symbol] symbol))
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(: :first)))
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:lookup-block
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(fn [self name]
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(if
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(-> (stream self.blocks)
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(: :skip 1)
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(: :filter (fn [block] (. block.symbols name)))
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(: :next))
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(. self.blocks 2)
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(. (. self.blocks 1) name)))
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:is-zp? (fn [self name] (< (. (self:lookup-block name) :org) 0x100))})
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(fn op-stream [env block]
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(-> (stream block.code)
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(: :map
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(fn [op]
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(if (= op.opcode :block)
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(: (one op env)
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:concat (op-stream (env:push op) op))
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(one op env))))
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(: :flatten)))
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(fn int8-to-bytes [i]
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(string.char (bit.band i 0xff)))
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(fn int16-to-bytes [i]
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(string.char (bit.band i 0xff) (bit.band (bit.rshift i 8) 0xff)))
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(fn program []
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{:symbols {}
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:start-symbol :main
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:add (fn [self name elem] (tset self.symbols name elem))
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:block (fn [self name org ...] (self:add name (block org ...)))
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:db (fn [self name org init] (self:add name (db org init)))
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:dw (fn [self name org init] (self:add name (dw org init)))
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:allot (fn [self name org size] (self:add name (allot org size)))
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:op-stream
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(fn [self block] (op-stream (make-env [self block]) block))
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:patch-addr-modes
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(fn [self]
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(each [name block (pairs self.symbols)]
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(each [op env (: (self:op-stream block) :iter)]
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(when (and op.mode (= (op.mode:sub 1 4) :addr))
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(let [zp-mode (.. :zp (op.mode:sub 5))
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abs-mode (.. :abs (op.mode:sub 5))
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is-zp (and ((. opcodes op.opcode) zp-mode) (env:is-zp? op.arg))]
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(set op.mode (if is-zp zp-mode abs-mode)))))))
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:allocate
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(fn [self org size org-addr]
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(var addr (. org-addr org))
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(when (= nil addr)
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(tset org-addr org org)
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(set addr org))
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(tset org-addr org (+ addr size))
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addr)
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:allocate-var-block
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(fn [self block org-addr]
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(set block.addr (self:allocate block.org block.size org-addr)))
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:allocate-code-block
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(fn [self block org-addr]
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(set block.addr (self:allocate block.org 0 org-addr))
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(each [op env (: (self:op-stream block) :iter)]
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(set op.addr (self:allocate block.org (opsize op) org-addr))))
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:allocate-addresses
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(fn [self]
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(let [org-addr {}]
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(each [name block (pairs self.symbols)]
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(match block.type
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:var (self:allocate-var-block block org-addr)
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:code (self:allocate-code-block block org-addr)))))
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:generate-var-block
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(fn [self block]
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(match block.size
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1 (int8-to-bytes (or block.init 0))
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2 (int16-to-bytes (or block.init 0))
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n (string.rep "\0" n)))
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:lookup-addr
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(fn [self sym env]
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(local op (env:lookup sym))
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(if op
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op.addr
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(tonumber sym)))
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:generate-op-arg
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(fn [self op env]
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(if
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(= op.mode :imm) (int8-to-bytes op.arg)
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(= op.mode :rel)
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(int8-to-bytes (- (self:lookup-addr op.arg env) (+ op.addr 2)))
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(= (size op.mode) 2) (int8-to-bytes (self:lookup-addr op.arg env))
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(= (size op.mode) 3) (int16-to-bytes (self:lookup-addr op.arg env))
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""))
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:generate-op
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(fn [self op env]
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(let [bytegen (. opcodes op.opcode)]
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(if bytegen
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(.. (int8-to-bytes (bytegen op.mode)) (self:generate-op-arg op env))
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"")))
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:generate-code-block
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(fn [self block]
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(var bytes "")
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(each [op env (: (self:op-stream block) :iter)]
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(set bytes (.. bytes (self:generate-op op env))))
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(set block.bytes bytes))
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:generate-bytes
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(fn [self]
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(each [name block (pairs self.symbols)]
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(match block.type
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:var (self:generate-var-block block)
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:code (self:generate-code-block block))))
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:assemble
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(fn [self]
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(self:patch-addr-modes)
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(self:allocate-addresses)
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(self:generate-bytes))})
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program |