94 lines
2.1 KiB
Racket
94 lines
2.1 KiB
Racket
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#lang racket
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(require (for-syntax syntax/parse))
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;-----------------------
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; Memory Data Structure
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;-----------------------
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; Methods for accessing a 16 bit addressing memory
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; including support for banking (planned) and
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; access controls for ROM (planned)
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;-----------------------
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; Needs:
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; Banking
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; Routes based on memory location
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; Banking based on memory
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; Registers:
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; Fast access
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; Hash?
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;
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(struct memory
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(registers state banks)
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#:transparent)
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(define (make-memory)
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(memory (make-regvec) (make-statevec) (make-bank)))
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(define (make-regvec)
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(make-vector 8))
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(define (make-statevec)
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(make-vector 2))
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(define (make-bank [init 0])
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(make-vector (expt 2 16)))
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(define (deref-state sym)
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(case sym
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[(state-PC) 0]
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[(state-SP) 1]
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[else (error "invalid state:" sym)]))
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(define (deref-reg sym)
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(case sym
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[(reg-A) 0]
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[(reg-F) 1]
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[(reg-B) 2]
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[(reg-C) 3]
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[(reg-D) 4]
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[(reg-E) 5]
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[(reg-H) 6]
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[(reg-L) 7]
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[else (error "invalid register:" sym)]))
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(define (get-reg sym memory)
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(vector-ref (memory-registers memory) (deref-reg sym)))
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(define (get-state sym memory)
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(vector-ref (memory-state memory) (deref-state sym)))
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(define (get-byte addr bank memory)
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(if (and (>= addr 0)
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(< addr 65536))
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(vector-ref (memory-banks memory) addr)
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(error (format "ERROR: address ~a out of bounds" addr))))
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(define (set-reg! sym memory val)
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(vector-set! (memory-registers memory) (deref-reg sym) (mod-8bit val)))
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(define (set-state! sym memory val)
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(vector-set! (memory-state memory) (deref-state sym) (mod-16bit val)))
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(define (set-byte! addr bank memory val)
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(if (and (>= addr 0)
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(< addr 65536))
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(vector-set! (memory-banks memory) addr (mod-8bit val))
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(error (format "ERROR: address ~a out of bounds" addr))))
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;----------------------------
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; define-8bit & define-16bit
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;----------------------------
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; composes operations with a modulo in order
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; to keep numbers within 8 bits
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;----------------------------
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(define (mod-8bit x)
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(modulo x 256))
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(define (mod-16bit x)
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(modulo x 65536))
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(provide (all-defined-out))
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