Make `get-pixels` fast:

Using bytevectors inside makes the process way faster and now can be
safely used in the loop, not only for debugging purposes

1 files changed, 14 insertions, 9 deletions

diff --git a/bytepusher.scm b/bytepusher.scm
index d72aaf4..2a3eb67 100644
--- a/bytepusher.scm
+++ b/bytepusher.scm
@@ -89,15 +89,6 @@
 
 
 ;; debug ----
-(define (get-pixels)
-  (let* ((initial   (get-initial-pixel))
-         (len       (* width height))
-         (base      (make-bytevector len)))
-    (bytevector-copy! memory initial base 0 len)
-    (uint-list->bytevector
-      (map pixel->color-fast (bytevector->u8-list base))
-      (endianness big)
-      4)))
 
 (define (peek-memory start end)
   (for-each (lambda (i) (display "0x")
@@ -126,6 +117,20 @@
 
 
 ;; rendering ----
+(define (get-pixels)
+  (let* ((initial   (get-initial-pixel))
+         (len       (* width height))
+         (base      (make-bytevector len))
+         (final     (make-bytevector (* 4 len))))
+    (bytevector-copy! memory initial base 0 len)
+    (let loop ((i 0))
+      (bytevector-u32-set! final
+                           (* 4 i)
+                           (pixel->color-fast (bytevector-u8-ref base i))
+                           (endianness big))
+      (unless (= i (- len 1)) (loop (+ 1 i))))
+      final))
+
 (define (make-display-texture renderer)
   (make-texture renderer 'argb8888 'streaming width height))