+(defun best-modular-version (width signedp)
+ ;; 1. exact width-matched :untagged
+ ;; 2. >/>= width-matched :tagged
+ ;; 3. >/>= width-matched :untagged
+ (let* ((uuwidths (modular-class-widths *untagged-unsigned-modular-class*))
+ (uswidths (modular-class-widths *untagged-signed-modular-class*))
+ (uwidths (merge 'list uuwidths uswidths #'< :key #'car))
+ (twidths (modular-class-widths *tagged-modular-class*)))
+ (let ((exact (find (cons width signedp) uwidths :test #'equal)))
+ (when exact
+ (return-from best-modular-version (values width :untagged signedp))))
+ (flet ((inexact-match (w)
+ (cond
+ ((eq signedp (cdr w)) (<= width (car w)))
+ ((eq signedp nil) (< width (car w))))))
+ (let ((tgt (find-if #'inexact-match twidths)))
+ (when tgt
+ (return-from best-modular-version
+ (values (car tgt) :tagged (cdr tgt)))))
+ (let ((ugt (find-if #'inexact-match uwidths)))
+ (when ugt
+ (return-from best-modular-version
+ (values (car ugt) :untagged (cdr ugt))))))))
+