also-alsa: Optimize for the usb8-typed buffers.

varjagg · Apr 9, 2022 · b2e8ee6 · b2e8ee6
1 parent 18032b7
commit b2e8ee6
Showing 1 changed file with 23 additions and 12 deletions.
diff --git a/also-alsa.lisp b/also-alsa.lisp
@@ -210,7 +210,9 @@
   pcs)
 
 (defun make-alsa-buffer (&key element-type size channels)
-  (make-array (* size channels) :element-type element-type))
+  (if (equalp element-type '(unsigned-byte 8))
+      (cffi:make-shareable-byte-vector (* size channels))
+      (make-array (* size channels) :element-type element-type)))
 
 (defun alsa-open (device buffer-size element-type &key direction (sample-rate 44100) (channels-count 2) buffer)
   (when buffer
@@ -310,10 +312,14 @@
   (assert (eql (direction pcm) :snd-pcm-stream-playback))
   (let* ((expected (/ (buffer-size pcm) (channels-count pcm)))
          (element-type (array-element-type (buffer pcm)))
-         (cffi-type (cffi::ensure-parsed-base-type
-                     (list :array (alsa-element-type element-type) expected)))
-         (result (with-foreign-array (ptr (buffer pcm) cffi-type)
-                   (snd-pcm-writei (deref (handle pcm)) ptr expected))))
+         (result (if (equalp element-type '(unsigned-byte 8))
+                     (with-pointer-to-vector-data (ptr (buffer pcm))
+                       (snd-pcm-writei (deref (handle pcm)) ptr expected))
+                     (with-foreign-array
+                         (ptr (buffer pcm)
+                              (cffi::ensure-parsed-base-type
+                               (list :array (alsa-element-type element-type) expected)))
+                       (snd-pcm-writei (deref (handle pcm)) ptr expected)))))
     (cond ((= result (- +epipe+))
            ;; Under run, so prepare and retry
            (alsa-warn "Underrun!")
@@ -326,13 +332,18 @@
   (assert (eql (direction pcm) :snd-pcm-stream-capture))
   (let* ((expected (/ (buffer-size pcm) (channels-count pcm)))
          (element-type (array-element-type (buffer pcm)))
-         (cffi-type (cffi::ensure-parsed-base-type
-                     (list :array (alsa-element-type element-type) expected)))
-         (result (with-foreign-array (ptr (buffer pcm) cffi-type)
-                   (prog1
-                       (snd-pcm-readi (deref (handle pcm)) ptr expected)
-                     (setf (slot-value pcm 'buffer)
-                           (foreign-array-to-lisp ptr cffi-type :element-type element-type))))))
+         (result (if (equalp element-type '(unsigned-byte 8))
+                     (with-pointer-to-vector-data (ptr (buffer pcm))
+                       (snd-pcm-readi (deref (handle pcm)) ptr
+                                      (/ (buffer-size pcm) (channels-count pcm))))
+                     (with-foreign-array
+                         (ptr (buffer pcm)
+                              (cffi::ensure-parsed-base-type
+                               (list :array (alsa-element-type element-type) expected)))
+                       (prog1
+                           (snd-pcm-readi (deref (handle pcm)) ptr expected)
+                         (setf (slot-value pcm 'buffer)
+                               (foreign-array-to-lisp ptr cffi-type :element-type element-type)))))))
     (unless (= result (/ (buffer-size pcm) (channels-count pcm)))
       (if (eql result (- +epipe+))
           (progn (alsa-warn "Underrun!") (snd-pcm-prepare (deref (handle pcm))))