realtek: pcs: simplify gray code to binary conversion

Gray conversion is b[i] = g[i] XOR g[i+1] XOR ... XOR g[n-1]
Make the code a 3 liner. For more details see [1].

[1] https://en.wikipedia.org/wiki/Gray_code#Converting_to_and_from_Gray_code

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/23984
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>

diff --git a/target/linux/realtek/files-6.18/drivers/net/pcs/pcs-rtl-otto.c b/target/linux/realtek/files-6.18/drivers/net/pcs/pcs-rtl-otto.c
index 2b84354fa4e7799c3179a8b872c3b75024fc2989..bb6b1c821918417ad372c7fe2b69c5b9a608828b 100644 (file)
--- a/target/linux/realtek/files-6.18/drivers/net/pcs/pcs-rtl-otto.c
+++ b/target/linux/realtek/files-6.18/drivers/net/pcs/pcs-rtl-otto.c
@@ -2144,31 +2144,15 @@ static void rtpcs_930x_sds_rxcal_leq_offset_manual(struct rtpcs_serdes *sds,
        }
 }
 
-#define GRAY_BITS 5
 static u32 rtpcs_930x_sds_rxcal_gray_to_binary(u32 gray_code)
 {
-       int i, j, m;
-       u32 g[GRAY_BITS];
-       u32 c[GRAY_BITS];
-       u32 leq_binary = 0;
+       u32 binary = gray_code;
 
-       for (i = 0; i < GRAY_BITS; i++)
-               g[i] = (gray_code & BIT(i)) >> i;
+       gray_code &= 0x1f; /* only lower 5 bits */
+       while (gray_code >>= 1)
+               binary ^= gray_code;
 
-       m = GRAY_BITS - 1;
-
-       c[m] = g[m];
-
-       for (i = 0; i < m; i++) {
-               c[i] = g[i];
-               for (j  = i + 1; j < GRAY_BITS; j++)
-                       c[i] = c[i] ^ g[j];
-       }
-
-       for (i = 0; i < GRAY_BITS; i++)
-               leq_binary += c[i] << i;
-
-       return leq_binary;
+       return binary;
 }
 
 static u32 rtpcs_930x_sds_rxcal_leq_read(struct rtpcs_serdes *sds)