Re: [RFC] bmac:change to use bitrev8() generic function
On Aug 10, 2015, at 20:02, David Laight david.lai...@aculab.com wrote: From: Tobias Klauser Sent: 10 August 2015 12:49 On 2015-08-10 at 11:53:41 +0200, yalin wang yalin.wang2...@gmail.com wrote: This change to use generic bitrev8() for bmac driver. ... @@ -871,7 +860,7 @@ bmac_addhash(struct bmac_data *bp, unsigned char *addr) if (!(*addr)) return; crc = bmac_crc((unsigned short *)addr) 0x3f; /* Big-endian alert! */ Why not *((u8 *)addr + 1) 0x3f - crc = reverse6[crc];/* Hyperfast bit-reversing algorithm */ + crc = bitrev8((u8)crc); No, this won't work. reverse6 works on 6 bit values, while bitrev8 works on 8bit values, e.g. reverse6[1] = 0x20, while bitrev8(1) = 0x80 You could use bitrev8(n) 2. But that is a 'strange' map of a 7-bit value to a 6-bit one. I thought it was more common for ethernet hardware to use the value of the crc register after all 6 bytes of the mac address had been processed. oh, my mistake, i will change it in V2 for review.-- To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC] bmac:change to use bitrev8() generic function
On 2015-08-10 at 11:53:41 +0200, yalin wang yalin.wang2...@gmail.com wrote:
This change to use generic bitrev8() for bmac driver.
Signed-off-by: yalin wang yalin.wang2...@gmail.com
---
drivers/net/ethernet/apple/bmac.c | 17 +++--
1 file changed, 3 insertions(+), 14 deletions(-)
diff --git a/drivers/net/ethernet/apple/bmac.c
b/drivers/net/ethernet/apple/bmac.c
index a65d7a6..e749747 100644
--- a/drivers/net/ethernet/apple/bmac.c
+++ b/drivers/net/ethernet/apple/bmac.c
@@ -22,6 +22,7 @@
#include linux/bitrev.h
#include linux/ethtool.h
#include linux/slab.h
+#include linux/bitrev.h
#include asm/prom.h
#include asm/dbdma.h
#include asm/io.h
@@ -805,18 +806,6 @@ static irqreturn_t bmac_txdma_intr(int irq, void *dev_id)
}
#ifndef SUNHME_MULTICAST
-/* Real fast bit-reversal algorithm, 6-bit values */
-static int reverse6[64] = {
- 0x0,0x20,0x10,0x30,0x8,0x28,0x18,0x38,
- 0x4,0x24,0x14,0x34,0xc,0x2c,0x1c,0x3c,
- 0x2,0x22,0x12,0x32,0xa,0x2a,0x1a,0x3a,
- 0x6,0x26,0x16,0x36,0xe,0x2e,0x1e,0x3e,
- 0x1,0x21,0x11,0x31,0x9,0x29,0x19,0x39,
- 0x5,0x25,0x15,0x35,0xd,0x2d,0x1d,0x3d,
- 0x3,0x23,0x13,0x33,0xb,0x2b,0x1b,0x3b,
- 0x7,0x27,0x17,0x37,0xf,0x2f,0x1f,0x3f
-};
-
static unsigned int
crc416(unsigned int curval, unsigned short nxtval)
{
@@ -871,7 +860,7 @@ bmac_addhash(struct bmac_data *bp, unsigned char *addr)
if (!(*addr)) return;
crc = bmac_crc((unsigned short *)addr) 0x3f; /* Big-endian alert! */
- crc = reverse6[crc];/* Hyperfast bit-reversing algorithm */
+ crc = bitrev8((u8)crc);
No, this won't work. reverse6 works on 6 bit values, while bitrev8 works
on 8bit values, e.g. reverse6[1] = 0x20, while bitrev8(1) = 0x80
--
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RE: [RFC] bmac:change to use bitrev8() generic function
From: Tobias Klauser Sent: 10 August 2015 12:49 On 2015-08-10 at 11:53:41 +0200, yalin wang yalin.wang2...@gmail.com wrote: This change to use generic bitrev8() for bmac driver. ... @@ -871,7 +860,7 @@ bmac_addhash(struct bmac_data *bp, unsigned char *addr) if (!(*addr)) return; crc = bmac_crc((unsigned short *)addr) 0x3f; /* Big-endian alert! */ Why not *((u8 *)addr + 1) 0x3f - crc = reverse6[crc];/* Hyperfast bit-reversing algorithm */ + crc = bitrev8((u8)crc); No, this won't work. reverse6 works on 6 bit values, while bitrev8 works on 8bit values, e.g. reverse6[1] = 0x20, while bitrev8(1) = 0x80 You could use bitrev8(n) 2. But that is a 'strange' map of a 7-bit value to a 6-bit one. I thought it was more common for ethernet hardware to use the value of the crc register after all 6 bytes of the mac address had been processed. David -- To unsubscribe from this list: send the line unsubscribe netdev in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
