diff options
| -rw-r--r-- | bytepusher.scm | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/bytepusher.scm b/bytepusher.scm index f28b961..9c8b96b 100644 --- a/bytepusher.scm +++ b/bytepusher.scm @@ -1,6 +1,7 @@ (define-module (bytepusher) #:use-module (rnrs bytevectors) #:use-module (srfi srfi-1) + #:use-module (srfi srfi-60) #:use-module (ice-9 binary-ports) #:use-module (sdl2) #:use-module (sdl2 render) @@ -39,13 +40,14 @@ ;; memory ---- (define (get-pc) - (+ (bytevector-u16-ref memory 3 (endianness big)) - (ash (bytevector-u8-ref memory 2) 16))) + (+ (ash (get-byte 4) 0) + (ash (get-byte 3) 8) + (ash (get-byte 2) 16))) (define (set-pc! value) - (let ((pc value)) - (bytevector-u16-set! memory 2 (ash pc -8) (endianness big)) - (bytevector-u8-set! memory 4 (ash pc -16)))) + (set-byte! 4 (ash value 0)) + (set-byte! 3 (ash value -8)) + (set-byte! 2 (ash value -16))) (define (get-addr pos) (+ (bytevector-u16-ref memory (+ 1 pos) (endianness big)) @@ -61,7 +63,7 @@ (bytevector-u8-ref memory n)) (define (set-byte! n v) - (bytevector-u8-set! memory n v)) + (bytevector-u8-set! memory n (logand v #xFF))) ;; ---- memory @@ -152,11 +154,20 @@ (bytevector-copy! program 0 memory 0 (bytevector-length program)))))) (define (execute! instruction-addr) + (call-with-values + (lambda () (load-instruction instruction-addr)) + (lambda (a b c) + (set-byte! b (get-byte a)) + (set-pc! c)))) + +(define (load-instruction instruction-addr) (let ((a (get-addr (+ 0 instruction-addr))) (b (get-addr (+ 3 instruction-addr))) (c (get-addr (+ 6 instruction-addr)))) - (set-byte! b (get-byte a)) - (set-pc! c))) + #;(display (string-append "a: " (number->string a 16) " ")) + #;(display (string-append "b: " (number->string b 16) " ")) + #;(display (string-append "c: " (number->string c 16) "\n")) + (values a b c))) (define (loop-frame!) (let loop ((count 65536)) |