Utilize new implementation of vm

2026-02-15 13:24:30 -06:00
parent d44f5d2851
commit b50d3109c0
6 changed files with 318 additions and 34 deletions
--- a/scmvm/vm/forth.scm
+++ b/scmvm/vm/forth.scm
@@ -0,0 +1,279 @@
+(define-module (scmvm vm forth)
+  #:use-module (scmvm vm2)
+  #:use-module (scmvm util stack)
+  #:use-module ((scheme base)
+                #:select (read-u8 read-bytevector))
+  #:use-module (rnrs bytevectors)
+  #:use-module (srfi srfi-9)
+  #:export ((make-forth-vm* . make-forth-vm)
+            forth-instruction-set
+            forth-vm-load-program!
+            forth-vm-run!
+            forth-vm-pc
+            forth-vm-pc-set!
+            forth-vm-memory-set!
+            forth-vm-memory-ref
+            forth-vm-data-stack))
+
+;;; IO
+(define *memory-size* 2048)
+
+(define* (make-ram #:optional (memory-size *memory-size*))
+  (make-bytevector memory-size #x00))
+
+(define (read-word)
+  "Read the next 32-bit value from (current-input-port)"
+  (let ([bv (read-bytevector 4)])
+    (bytevector-s32-ref bv 0 (native-endianness))))
+
+
+;;; VM
+(define-record-type <forth-vm>
+  (make-forth-vm instruction-set registers)
+  forth-vm?
+  (instruction-set forth-vm-instruction-set)
+  (registers forth-vm-registers forth-vm-registers-set!))
+
+(define* (make-forth-vm* instruction-set #:key stack-size memory-size)
+  "Create a fresh VM, with optional stack and memory sizes"
+  (define registers (register-set '(*data-stack* *ret-stack* *pc* *ram* *vm-exit*)))
+  ((hash-ref registers '*pc*) 1)
+  ((hash-ref registers '*data-stack*) (if stack-size (make-stack stack-size) (make-stack)))
+  ((hash-ref registers '*ret-stack*) (if stack-size (make-stack stack-size) (make-stack)))
+  ((hash-ref registers '*ram*) (if memory-size (make-ram memory-size) (make-ram)))
+  (make-forth-vm instruction-set registers))
+
+(define *vm* (make-parameter #f))
+
+(define-syntax-rule (with-forth-vm-registers (reg ...) expr ...)
+  (let ([reg (hash-ref (forth-vm-registers (*vm*)) 'reg)] ...)
+    expr ...))
+
+(define (ram-word-ref k)
+  (with-forth-vm-registers
+   (*ram*)
+   (if (< k 1)
+       (error "null memory read")
+       (bytevector-s32-native-ref (*ram*) (1- k)))))
+
+(define (ram-byte-ref k)
+  (with-forth-vm-registers
+   (*ram*)
+   (if (< k 1)
+       (error "null memory read")
+       (bytevector-u8-ref (*ram*) (1- k)))))
+
+(define (ram-word-set! k v)
+  (with-forth-vm-registers
+   (*ram*)
+   (if (< k 1)
+       (error "null memory write")
+       (bytevector-s32-native-set! (*ram*) (1- k) v))))
+
+(define (jump! x)
+  (with-forth-vm-registers
+   (*pc*)
+   (*pc* (logand #x2fffffff x))))
+
+(define (fetch-byte!)
+  (with-forth-vm-registers
+   (*pc*)
+   (let* ([byte (ram-byte-ref (*pc*))])
+     (*pc* (+ (*pc*) 1))
+     byte)))
+
+(define (fetch-word!)
+  (with-forth-vm-registers
+   (*ram* *pc*)
+   (let* ([word (ram-word-ref (*pc*))])
+     (*pc* (+ (*pc*) 4))
+     word)))
+
+(define (forth-vm-pc vm)
+  (parameterize ([*vm* vm])
+    (with-forth-vm-registers
+     (*pc*)
+     (*pc*))))
+
+(define (forth-vm-pc-set! vm k)
+  (parameterize ([*vm* vm])
+    (with-forth-vm-registers
+     (*pc*)
+     (*pc* k))))
+
+(define (forth-vm-memory-set! vm k v)
+  (parameterize ([*vm* vm])
+    (ram-word-set! k v)))
+
+(define (forth-vm-memory-ref vm k)
+  (parameterize ([*vm* vm])
+    (with-forth-vm-registers
+     (*ram*)
+     (ram-word-ref k))))
+
+(define (forth-vm-data-stack vm)
+  (parameterize ([*vm* vm])
+    (with-forth-vm-registers
+     (*data-stack*)
+     (*data-stack*))))
+
+ ;;; Instruction set
+(define-instruction-set (forth-instruction-set *pc* *ram* *data-stack* *ret-stack* *vm-exit*)
+  (define-instruction (push #x01)
+    (stack-push (*data-stack*) (fetch-word!)))
+  
+  (define-instruction (! #x02)
+    (let ([addr (stack-pop (*data-stack*))]
+          [v (stack-pop (*data-stack*))])
+      (ram-word-set! addr v)))
+  
+  (define-instruction (@ #x03)
+    (let* ([addr (stack-pop (*data-stack*))]
+           [v (ram-word-ref addr)])
+      (stack-push (*data-stack*) v)))
+  
+  (define-instruction (+ #x04)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) (+ v1 v2))))
+  
+  (define-instruction (- #x05)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) (- v1 v2))))
+  
+  (define-instruction (and #x06)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) (logand v1 v2))))
+
+  (define-instruction (or #x07)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) (logior v1 v2))))
+
+  (define-instruction (nand #x08)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) (if (zero? (logand v1 v2)) 1 0))))
+
+  (define-instruction (nor #x09)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) (if (zero? (logior v1 v2)) 1 0))))
+
+  (define-instruction (xor #x0a)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) (logxor v1 v2))))
+
+  (define-instruction (= #x0b)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (if (= v1 v2)
+          (stack-push (*data-stack*) 1)
+          (stack-push (*data-stack*) 0))))
+
+  (define-instruction (> #x0c)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (if (> v1 v2)
+          (stack-push (*data-stack*) 1)
+          (stack-push (*data-stack*) 0))))
+
+  (define-instruction (< #x0d)
+    (let ([v2 (stack-pop (*data-stack*))]
+          [v1 (stack-pop (*data-stack*))])
+      (if (< v1 v2)
+          (stack-push (*data-stack*) 1)
+          (stack-push (*data-stack*) 0))))
+
+  (define-instruction (jmp #x0e)
+    (jump! (stack-pop (*data-stack*))))
+
+  (define-instruction (branch #x0f)
+    (let* ([addr (stack-pop (*data-stack*))]
+           [test (stack-pop (*data-stack*))])
+      (when (zero? test)
+        (jump! addr))))
+
+  (define-instruction (call #x10)
+    (let ([addr (stack-pop (*data-stack*))])
+      (stack-push (*ret-stack*) (*pc*))
+      (jump! addr)))
+
+  (define-instruction (return #x11)
+    (jump! (stack-pop (*ret-stack*))))
+
+  (define-instruction (>R #x12)
+    (stack-push (*ret-stack*) (stack-pop (*data-stack*))))
+
+  (define-instruction (R> #x13)
+    (stack-push (*data-stack*) (stack-pop (*ret-stack*))))
+
+  (define-instruction (drop #x14)
+    (stack-pop (*data-stack*)))
+
+  (define-instruction (nip #x15)
+    (let ([v (stack-pop (*data-stack*))])
+      (stack-pop (*data-stack*))
+      (stack-push (*data-stack*) v)))
+
+  (define-instruction (dup #x16)
+    (stack-push (*data-stack*) (stack-peek (*data-stack*))))
+
+  (define-instruction (swap #x17)
+    (stack-swap (*data-stack*)))
+
+  (define-instruction (rot #x18)
+    (let* ([a (stack-pop (*data-stack*))]
+           [b (stack-pop (*data-stack*))]
+           [c (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) a)
+      (stack-push (*data-stack*) c)
+      (stack-push (*data-stack*) b)))
+
+  (define-instruction (over #x19)
+    (let* ([a (stack-pop (*data-stack*))]
+           [b (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) b)
+      (stack-push (*data-stack*) a)
+      (stack-push (*data-stack*) b)))
+
+  (define-instruction (not #x1a)
+    (let ([a (stack-pop (*data-stack*))])
+      (stack-push (*data-stack*) (if (zero? a) 1 0))))
+
+  (define-instruction (set! #x1b)
+    ;; use let* to induce an order of evaluation
+    (let* ([idx (stack-pop (*data-stack*))]
+           [obj (stack-pop (*data-stack*))])
+      (stack-set! (*data-stack*) idx obj)))
+
+  (define-instruction (bye #xff)
+    (*vm-exit* #t)))
+
+;;; Execution
+(define* (forth-vm-run! vm #:optional debugger)
+  "Begin execution at pc"
+  (define caller (instruction-set-caller (forth-vm-instruction-set vm)
+                                         (forth-vm-registers vm)))
+  (parameterize ([*vm* vm])
+    (with-forth-vm-registers
+     (*vm-exit*)
+     (let lp () 
+       (when debugger
+         (debugger))
+       (define op (fetch-byte!))
+       (caller op)
+       (unless (*vm-exit*) (lp))))))
+
+(define (forth-vm-load-program! vm prgm)
+  "Loads the bytevector into the vm, starting at memory address 1"
+  (parameterize ([*vm* vm])
+    (with-forth-vm-registers
+     (*ram*)
+     (let ([ram (*ram*)])
+       (bytevector-copy! prgm 0
+                         ram 0
+                         (bytevector-length prgm))))))