Jeremy Penner
d2ff69258f
asm: allow computed addresses, not just immediate mode values map llissp source to assembly
58 lines
2.4 KiB
Fennel
58 lines
2.4 KiB
Fennel
(import-macros {:sss ! : compile} :ssc.macros)
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(local {: addr-parser} (require :asm.65816))
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#(compile $1
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[(do (set $1.TASK-NEXT ($1:alloc-dp-var))
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(set $1.TASK-STACK ($1:alloc-dp-var))
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(set $1.TASK-MAILBOX ($1:alloc-dp-var))
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nil)]
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(global word old-dp 0)
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(global word old-sp 0)
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(form save-dp-sp [#[:block [:tdc] [:sta :old-dp] [:tsc] [:sta :old-sp]]])
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(form restore-dp-sp [#[:block [:lda :old-dp] [:tcd] [:lda :old-sp] [:tcs]]])
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(form save-6502-stack [#[:block [:tsc] [:tay] [:and 0xff] [:ora 0x100] [:tax] [:eor 0xffff] [:clc] [:adc 0x200] [:phb] [:mvn 0 0] [:plb]]])
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(form restore-6502-stack [#[:block [:tsc] [:tax] [:and 0xff] [:ora 0x100] [:tay] [:eor 0xffff] [:clc] [:adc 0x200] [:phb] [:mvn 0 0] [:plb]]])
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; 0x1ef = 0x1ef-0x1ff = 0x0f -> 0x7f
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(const task-size 0x100)
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(global word first-task)
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(global word last-task)
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(form set-task-base [(fn [ssc task-base]
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[:block [:lda task-base] [:tcd]
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[:sta ssc.TASK-NEXT] [:sta :first-task] [:sta :last-task]
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[:tsc] [:and 0xff] [:ora task-base] [:tcs]])])
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(fn yield ()
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(asm (tsc) (sta [$1.TASK-STACK])
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(lda [$1.TASK-NEXT]) (tcd)
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(lda [$1.TASK-STACK]) (tcs)))
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(fn yield-forever () (while true (yield)))
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(fn reset-task (task f)
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; setup stack
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(word! (long (+ task 0xfe)) (- (ref yield-forever) 1)) ; allow tasks to return; rts adds one to the value on the stack for the next pc
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(word! (long (+ task 0xfc)) (- f 1)) ; yield will return to this address
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(word! (long (+ task [(addr-parser $1.TASK-STACK)])) (+ task 0xfb)) ; stack pointer is the next available location
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(word! (long (+ task [(addr-parser $1.TASK-MAILBOX)])) 0) ; clear mailbox
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)
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(fn new-task (f)
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(let (next-task (+ last-task task-size))
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(reset-task next-task f)
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(word! (long (+ next-task [(addr-parser $1.TASK-NEXT)])) first-task) ; the last task yields to the first task, round-robin
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(word! (long (+ last-task [(addr-parser $1.TASK-NEXT)])) next-task) ; the previously-last task now yields to us
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(set! last-task next-task)
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next-task))
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(form current-task [#[:tdc]])
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(fn task-send (task msg)
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(word! (long (+ task [(addr-parser $1.TASK-MAILBOX)])) msg))
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(form task-peek [#[:lda $1.TASK-MAILBOX]])
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(fn task-recv ()
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(asm (ldx [$1.TASK-MAILBOX]) (lda 0) (sta [$1.TASK-MAILBOX]) (txa))))
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