Move further code to common, rename to assembler (last restructure I promise)

scmvm/assembler.scm

@@ -0,0 +1,80 @@
+(define-module (scmvm assembler)
+  #:use-module (scmvm vm)
+  #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-9)
+  #:use-module (rnrs bytevectors)
+  #:use-module ((scheme base) #:select (write-bytevector))
+  #:export ((make-assembler* . make-assembler)
+	    assembler?
+	    assembler-labels
+	    emit-label
+	    emit-instruction
+	    emit-literal
+	    emit-reference
+	    finalize-references
+	    assembler-dump-program))
+
+(define (make-label) (cons #f '()))
+
+(define-record-type <assembler>
+  (make-assembler pos buf labels)
+  assembler?
+  (pos assembler-pos assembler-pos-set!)
+  (buf assembler-buf assembler-buf-set!)
+  (labels assembler-labels))
+
+(define (make-assembler*)
+  (make-assembler 0 (make-bytevector 1024) (make-hash-table)))
+
+(define (assembler-buf-grow! asm)
+  (let ([buf (make-bytevector (ash (bytevector-length (assembler-buf asm)) -1))])
+    (bytevector-copy! (assembler-buf asm) 0 buf 0 (bytevector-length (assembler-buf asm)))
+    (assembler-buf-set! asm buf)))
+
+(define* (write-word word asm #:optional (pos (assembler-pos asm)))
+  (when (> (+ pos 4) (bytevector-length (assembler-buf asm)))
+    (assembler-buf-grow! asm))
+  (bytevector-u32-native-set! (assembler-buf asm) pos word))
+
+(define* (write-byte byte asm #:optional (pos (assembler-pos asm)))
+  (when (> (+ pos 1) (bytevector-length (assembler-buf asm)))
+    (assembler-buf-grow! asm))
+  (bytevector-u8-set! (assembler-buf asm) pos byte))
+
+(define (assembler-label-add-reference asm name addr)
+  (when (not (hash-ref (assembler-labels asm) name))
+    (hash-set! (assembler-labels asm) name (make-label)))
+  (let ([label (hash-ref (assembler-labels asm) name)])
+    (set-cdr! label (cons addr (cdr label)))))
+
+(define (assembler-label-add-value asm name val)
+  (when (not (hash-ref (assembler-labels asm) name))
+    (hash-set! (assembler-labels asm) name (make-label)))
+  ;; 1+ to fudge for null pointers
+  (set-car! (hash-ref (assembler-labels asm) name) (1+ val)))
+
+(define (emit-label asm name)
+  (assembler-label-add-value asm name (assembler-pos asm)))
+
+(define (emit-instruction asm inst)
+  (let ([inst-object (assq inst *instruction-set*)])
+    (write-byte (instruction-code inst-object) asm)
+    (assembler-pos-set! asm (+ (assembler-pos asm) 1))))
+
+(define (emit-literal asm val)
+  (write-word val asm)
+  (assembler-pos-set! asm (+ (assembler-pos asm) 4)))
+
+(define (emit-reference asm name)
+  (assembler-label-add-reference asm name (assembler-pos asm))
+  (assembler-pos-set! asm (+ (assembler-pos asm) 4)))
+
+(define (finalize-references asm)
+  (define (install-location _name label)
+    (for-each
+     (cute write-word (car label) asm <>)
+     (cdr label)))
+  (hash-for-each install-location (assembler-labels asm)))
+
+(define (assembler-dump-program asm port)
+  (write-bytevector (assembler-buf asm) port 0 (assembler-pos asm)))