--- zzzz-none-000/linux-3.10.107/drivers/isdn/mISDN/dsp_audio.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/isdn/mISDN/dsp_audio.c	2021-02-04 17:41:59.000000000 +0000
@@ -13,6 +13,7 @@
 #include <linux/mISDNif.h>
 #include <linux/mISDNdsp.h>
 #include <linux/export.h>
+#include <linux/bitrev.h>
 #include "core.h"
 #include "dsp.h"
 
@@ -137,27 +138,14 @@
 	return ulawbyte;
 }
 
-static int reverse_bits(int i)
-{
-	int z, j;
-	z = 0;
-
-	for (j = 0; j < 8; j++) {
-		if ((i & (1 << j)) != 0)
-			z |= 1 << (7 - j);
-	}
-	return z;
-}
-
-
 void dsp_audio_generate_law_tables(void)
 {
 	int i;
 	for (i = 0; i < 256; i++)
-		dsp_audio_alaw_to_s32[i] = alaw2linear(reverse_bits(i));
+		dsp_audio_alaw_to_s32[i] = alaw2linear(bitrev8((u8)i));
 
 	for (i = 0; i < 256; i++)
-		dsp_audio_ulaw_to_s32[i] = ulaw2linear(reverse_bits(i));
+		dsp_audio_ulaw_to_s32[i] = ulaw2linear(bitrev8((u8)i));
 
 	for (i = 0; i < 256; i++) {
 		dsp_audio_alaw_to_ulaw[i] =
@@ -176,13 +164,13 @@
 		/* generating ulaw-table */
 		for (i = -32768; i < 32768; i++) {
 			dsp_audio_s16_to_law[i & 0xffff] =
-				reverse_bits(linear2ulaw(i));
+				bitrev8(linear2ulaw(i));
 		}
 	} else {
 		/* generating alaw-table */
 		for (i = -32768; i < 32768; i++) {
 			dsp_audio_s16_to_law[i & 0xffff] =
-				reverse_bits(linear2alaw(i));
+				bitrev8(linear2alaw(i));
 		}
 	}
 }