core, make dc filter reacting faster (arm)

diff --git a/pico/sound/mix_arm.S b/pico/sound/mix_arm.S
index 64383c3..486aa5b 100644 (file)
--- a/pico/sound/mix_arm.S
+++ b/pico/sound/mix_arm.S
@@ -299,7 +299,7 @@ m16_32_rsm_end:
 @ in=int_sample (max 20 bit), y=filter memory, r8=tmp
 .macro DCfilt in y
     rsb     r8, \y, \in, lsl #12       @ fixpoint 20.12
-    add     \y, \y, r8, asr #12                @ alpha = 1-1/4094
+    add     \y, \y, r8, asr #9         @ alpha = 1-1/512
     sub     \in, \in, \y, asr #12
 .endm