1 files changed, 66 insertions, 0 deletions
diff --git a/src/emit.lisp b/src/emit.lisp
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+++ b/src/emit.lisp
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+(in-package #:emit)
+
+(defun fits-in-X-bits (n)
+  "Returns the number of bits required to represent N"
+  (ceiling (/ (log (ceiling n (log 2))) (log 2))))
+
+(defmacro generate-type-map (ops)
+  "Generates an alist where the key corresponds to an element in
+OPS, while the value is the index of that key (padded to the minimum
+number of bits required to represent all
+concatenated with TYPE."
+  `(let ((i 0)
+         (opsize (fits-in-X-bits (length ,ops))))
+     (mapcar (lambda (x)
+               (incf i)
+               (cons x (util:format-as-binary i opsize)))
+             ,ops)))
+
+(defvar mnemonic-loc
+  `(,@(generate-type-map util:r-type)
+    ,@(generate-type-map util:i-type)
+    ,@(generate-type-map util:j-type))
+  "An alist mapping known mnemonics to their binary representation.")
+
+(defun lookup-mnemonic (mnemonic)
+  (cdr (assoc mnemonic mnemonic-loc :test #'string=)))
+
+(defun p (d x)
+  (append x d))
+
+(defun d (&rest lst)
+  (mapcar (lambda (x) (util:format-as-binary x 32)) lst))
+
+(defun x (&rest lst)
+  lst)
+
+(defun r (mnemonic s1 s2 d)
+  (concatenate
+   'string (format nil "~10,'0d" 0) d s2 s1 (lookup-mnemonic mnemonic) "00"))
+
+(defun i (mnemonic s d i)
+  (concatenate
+   'string (util:format-as-binary i 16) d s (lookup-mnemonic mnemonic) "01"))
+
+(defun j (mnemonic b d)
+  (concatenate
+   'string (util:format-as-binary d 21) b (lookup-mnemonic mnemonic) "10"))
+
+(defun rr (val)
+  (if (<= 0 val 23)
+      (util:format-as-binary val 5)
+      (error (format nil "~a is not a valid register id!~%" val))))
+
+(defun imm (val) val)
+
+(defun l (l s)
+  (let ((d (util:get-label l)))
+    (- d s)))
+
+(defun var (s)
+  (let ((pos (util:get-variable s)))
+    (+ pos parse:line-number)))
+
+(defun emit (p)
+  (format t "~a~%" p)
+  (eval p))