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authorGeorge Spelvin <linux@sciencehorizons.net>2016-05-27 06:00:23 +0300
committerGeorge Spelvin <linux@sciencehorizons.net>2016-05-28 22:42:51 +0300
commitef703f49a6c5b909a85149bb6625c4ed0d697186 (patch)
tree4207abfae54812ba02e76ad6450ce4d0facd6b41 /drivers
parent92d567740f2ab5937b2c23bee94ea4b284bb1f98 (diff)
downloadlinux-ef703f49a6c5b909a85149bb6625c4ed0d697186.tar.xz
Eliminate bad hash multipliers from hash_32() and hash_64()
The "simplified" prime multipliers made very bad hash functions, so get rid of them. This completes the work of 689de1d6ca. To avoid the inefficiency which was the motivation for the "simplified" multipliers, hash_64() on 32-bit systems is changed to use a different algorithm. It makes two calls to hash_32() instead. drivers/media/usb/dvb-usb-v2/af9015.c uses the old GOLDEN_RATIO_PRIME_32 for some horrible reason, so it inherits a copy of the old definition. Signed-off-by: George Spelvin <linux@sciencehorizons.net> Cc: Antti Palosaari <crope@iki.fi> Cc: Mauro Carvalho Chehab <m.chehab@samsung.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/media/usb/dvb-usb-v2/af9015.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/media/usb/dvb-usb-v2/af9015.c b/drivers/media/usb/dvb-usb-v2/af9015.c
index 95a7388e89d4..09e0f58f6bb7 100644
--- a/drivers/media/usb/dvb-usb-v2/af9015.c
+++ b/drivers/media/usb/dvb-usb-v2/af9015.c
@@ -398,6 +398,8 @@ error:
}
#define AF9015_EEPROM_SIZE 256
+/* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
+#define GOLDEN_RATIO_PRIME_32 0x9e370001UL
/* hash (and dump) eeprom */
static int af9015_eeprom_hash(struct dvb_usb_device *d)