Implement assembly emission, allowing execution of trivial programs

Rewrite preprocess to return an input port rather than a temporary file.

2 files changed, 49 insertions, 14 deletions

diff --git a/src/modules/emitter/emitter.scm b/src/modules/emitter/emitter.scm
new file mode 100644
index 0000000..5e4b7d4
--- /dev/null
+++ b/src/modules/emitter/emitter.scm
@@ -0,0 +1,43 @@
+(define-module (modules emitter emitter)
+  #:use-module (modules ast syntax-tree)
+  #:use-module (modules ast assembly-tree)
+  #:export (e-program))
+
+
+(define emit #f)
+(define emitln #f)
+(let ((p ""))
+  (set! emit
+        (lambda (str)
+          (set! p (string-append/shared p str))
+          p))
+  (set! emitln
+        (lambda (str)
+          (emit (string-append/shared str "\n"))
+          p))
+  )
+
+(define (e-program p)
+  (e-subroutine (program-function p))
+  (emitln ".section .note.GNU-stack,\"\",@progbits"))
+
+(define (e-subroutine s)
+  (let ((label (subroutine-label s)))
+    (emitln (format #f "    .globl ~a" label))
+    (emitln (format #f "~a:" label)))
+  (e-instructions (subroutine-instructions s)))
+
+(define (e-instructions lst)
+  (unless (null? lst)
+    (begin (e-instruction (car lst))
+           (e-instructions (cdr lst)))))
+
+(define (e-instruction i)
+  (emit (format #f "    ~a" (instruction-operator i)))
+  (let ((oper1 (instruction-operand-1 i))
+        (oper2 (instruction-operand-2 i)))
+    (when oper1
+      (emit (format #f " ~a" oper1))
+      (when oper2
+        (emit (format #f ", ~a" oper2)))))
+  (emitln ""))
diff --git a/src/modules/generator/generator.scm b/src/modules/generator/generator.scm
index 4c08e32..53be252 100644
--- a/src/modules/generator/generator.scm
+++ b/src/modules/generator/generator.scm
@@ -1,30 +1,22 @@
 (define-module (modules generator generator)
   #:use-module (modules ast syntax-tree)
   #:use-module (modules ast assembly-tree)
-  #:export (generate))
+  #:export (g-program))
 
-(define (generate node)
-  (cond
-   ((program? node) (g-program node))
-   ((function? node) (g-function node))
-   ((stmt? node) (g-stmt node))
-   ((expr? node) (g-expr node))
-   ((id? node) (g-id node))
-   (else (error "Unknown AST element"))))
 
 (define (g-program p)
-  (make-program (generate (program-function p))))
+  (make-program (g-function (program-function p))))
 
 (define (g-function f)
-  (make-subroutine (generate (function-id f))
-                   (generate (function-stmt f))))
+  (make-subroutine (g-id (function-id f))
+                   (g-stmt (function-stmt f))))
 
 (define (g-stmt s)
-  (generate (stmt-expr s)))
+  (g-expr (stmt-expr s)))
 
 (define (g-expr e)
   ;; for now, we assume only 'return'!
-  (list (make-instruction "mov1" "%eax" "$2")
+  (list (make-instruction "movl" (string-append/shared "$" (number->string (expr-int e))) "%eax")
         (make-instruction "ret" #f #f)))
 
 (define (g-id i)