aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--ChangeLog4
-rw-r--r--libmpio/src/ecc.c160
2 files changed, 60 insertions, 104 deletions
diff --git a/ChangeLog b/ChangeLog
index 2eb926d..d27d477 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
-2003-04-29 Markus Germeier <mager@tzi.de>
+2003-04-30 Markus Germeier <mager@tzi.de>
+ * libmpio/src/ecc.c: cleaned up ECC code
+2003-04-29 Markus Germeier <mager@tzi.de>
* libmpio/src/ecc.c (mpio_ecc_256_check):
fix level for debug messages
diff --git a/libmpio/src/ecc.c b/libmpio/src/ecc.c
index 4082afe..58aaa1e 100644
--- a/libmpio/src/ecc.c
+++ b/libmpio/src/ecc.c
@@ -1,5 +1,5 @@
/*
- * $Id: ecc.c,v 1.4 2003/04/29 15:11:35 germeier Exp $
+ * $Id: ecc.c,v 1.5 2003/04/30 21:23:04 germeier Exp $
*
* libmpio - a library for accessing Digit@lways MPIO players
* Copyright (C) 2002, 2003 Markus Germeier
@@ -23,15 +23,12 @@
#include "ecc.h"
#include "debug.h"
-BYTE get_bit(BYTE, int);
-
-/* TODO: fix correctable errors */
-
-inline BYTE
-get_bit(BYTE d, int offset)
-{
- return ((d >> offset) & 0x01 );
-}
+#define GET_BIT(d, o) (((d) >> (o)) & 0x01 )
+#define XOR_BITS(d, x1, x2, x3, x4) (GET_BIT((d), (x1)) ^ \
+ GET_BIT((d), (x2)) ^ \
+ GET_BIT((d), (x3)) ^ \
+ GET_BIT((d), (x4)))
+#define ADD_BITS(c, d1, d2, v) if ((c)) d1 ^= (v); else d2 ^= (v)
int
mpio_ecc_256_gen(BYTE *data, BYTE *ecc)
@@ -68,96 +65,50 @@ mpio_ecc_256_gen(BYTE *data, BYTE *ecc)
p1024=p1024_=0;
/* vertical */
- for (i=0; i<256; i++) {
-
+ for (i=0; i<256; i++) {
/* p1, p1_ */
- p1 ^= (get_bit(data[i], 7) ^
- get_bit(data[i], 5) ^
- get_bit(data[i], 3) ^
- get_bit(data[i], 1));
- p1_^= (get_bit(data[i], 6) ^
- get_bit(data[i], 4) ^
- get_bit(data[i], 2) ^
- get_bit(data[i], 0));
+ p1 ^= XOR_BITS(data[i], 7, 5, 3, 1);
+ p1_^= XOR_BITS(data[i], 6, 4, 2, 0);
/* p2, p2_ */
- p2 ^= (get_bit(data[i], 7) ^
- get_bit(data[i], 6) ^
- get_bit(data[i], 3) ^
- get_bit(data[i], 2));
- p2_^= (get_bit(data[i], 5) ^
- get_bit(data[i], 4) ^
- get_bit(data[i], 1) ^
- get_bit(data[i], 0));
+ p2 ^= XOR_BITS(data[i], 7, 6, 3, 2);
+ p2_^= XOR_BITS(data[i], 5, 4, 1, 0);
/* p4, p4_ */
- p4 ^= (get_bit(data[i], 7) ^
- get_bit(data[i], 6) ^
- get_bit(data[i], 5) ^
- get_bit(data[i], 4));
- p4_^= (get_bit(data[i], 3) ^
- get_bit(data[i], 2) ^
- get_bit(data[i], 1) ^
- get_bit(data[i], 0));
+ p4 ^= XOR_BITS(data[i], 7, 6, 5, 4);
+ p4_^= XOR_BITS(data[i], 3, 2, 1, 0);
}
/* horizontal */
for (i=0; i<8; i++) {
-
- for (j=0; j<256; j++) {
-
+ for (j=0; j<256; j++) {
/* p08, p08_ */
- if ((j & 0x01) == 0)
- p08_^= get_bit(data[j], i);
- if ((j & 0x01) == 1)
- p08 ^= get_bit(data[j], i);
+ ADD_BITS(GET_BIT(j, 0), p08, p08_, GET_BIT(data[j], i));
/* p16, p16_ */
- if (((j/2) & 0x01) == 0)
- p16_^= get_bit(data[j], i);
- if (((j/2) & 0x01) == 1)
- p16^= get_bit(data[j], i);
+ ADD_BITS(GET_BIT(j, 1), p16, p16_, GET_BIT(data[j], i));
/* p32, p32_ */
- if (((j/4) & 0x01) == 0)
- p32_^= get_bit(data[j], i);
- if (((j/4) & 0x01) == 1)
- p32^= get_bit(data[j], i);
+ ADD_BITS(GET_BIT(j, 2), p32, p32_, GET_BIT(data[j], i));
/* p64, p64_ */
- if (((j/8) & 0x01) == 0)
- p64_^= get_bit(data[j], i);
- if (((j/8) & 0x01) == 1)
- p64^= get_bit(data[j], i);
-
+ ADD_BITS(GET_BIT(j, 3), p64, p64_, GET_BIT(data[j], i));
/* p0128, p0128_ */
- if (((j/16) & 0x01) == 0)
- p0128_^= get_bit(data[j], i);
- if (((j/16) & 0x01) == 1)
- p0128 ^= get_bit(data[j], i);
+ ADD_BITS(GET_BIT(j, 4), p0128, p0128_, GET_BIT(data[j], i));
/* p0256, p0256_ */
- if (((j/32) & 0x01) == 0)
- p0256_^= get_bit(data[j], i);
- if (((j/32) & 0x01) == 1)
- p0256^= get_bit(data[j], i);
+ ADD_BITS(GET_BIT(j, 5), p0256, p0256_, GET_BIT(data[j], i));
/* p0512, p0512_ */
- if (((j/64) & 0x01) == 0)
- p0512_^= get_bit(data[j], i);
- if (((j/64) & 0x01) == 1)
- p0512^= get_bit(data[j], i);
+ ADD_BITS(GET_BIT(j, 6), p0512, p0512_, GET_BIT(data[j], i));
/* p1024, p1024_ */
- if (((j/128) & 0x01) == 0)
- p1024_^= get_bit(data[j], i);
- if (((j/128) & 0x01) == 1)
- p1024^= get_bit(data[j], i);
-
+ ADD_BITS(GET_BIT(j, 7), p1024, p1024_, GET_BIT(data[j], i));
}
}
+ /* calculate actual ECC */
ecc[0]=~((p64 << 7) | (p64_ << 6) |
(p32 << 5) | (p32_ << 4) |
(p16 << 3) | (p16_ << 2) |
@@ -186,51 +137,54 @@ mpio_ecc_256_check(BYTE *data, BYTE *ecc)
int v, i;
mpio_ecc_256_gen(data, own_ecc);
- if ((own_ecc[0]^ecc[0])|
- (own_ecc[1]^ecc[1])|
- (own_ecc[2]^ecc[2])) {
- debugn(2, "ECC %2x %2x %2x vs. %2x %2x %2x\n",
- ecc[0], ecc[1], ecc[2], own_ecc[0], own_ecc[1], own_ecc[2]);
- check[0] = (ecc[0] ^ own_ecc[0]);
- check[1] = (ecc[1] ^ own_ecc[1]);
- check[2] = (ecc[2] ^ own_ecc[2]);
+
+ check[0] = (ecc[0] ^ own_ecc[0]);
+ check[1] = (ecc[1] ^ own_ecc[1]);
+ check[2] = (ecc[2] ^ own_ecc[2]);
+
+ /* if ECC is wrong, try to fix one-bit errors */
+ if (check[0] | check[1] | check[2]) {
+ debugn(3, "ECC %2x %2x %2x vs. %2x %2x %2x\n",
+ ecc[0], ecc[1], ecc[2], own_ecc[0], own_ecc[1], own_ecc[2]);
v=1;
for(i=0; i<4; i++)
{
- if (!((get_bit(check[1], i*2) ^
- (get_bit(check[1], i*2+1)))))
+ if (!( (GET_BIT(check[1], i*2) ^
+ (GET_BIT(check[1], i*2+1)))))
v=0;
- if (!((get_bit(check[0], i*2) ^
- (get_bit(check[0], i*2+1)))))
+ if (!( (GET_BIT(check[0], i*2) ^
+ (GET_BIT(check[0], i*2+1)))))
v=0;
}
for(i=1; i<4; i++)
{
- if (!((get_bit(check[2], i*2) ^
- (get_bit(check[2], i*2+1)))))
+ if (!( (GET_BIT(check[2], i*2) ^
+ (GET_BIT(check[2], i*2+1)))))
v=0;
}
if (v) {
- debugn(2, "correctable error detected ... fixing the bit\n");
- line = get_bit(check[1], 7) * 128 +
- get_bit(check[1], 5) * 64 +
- get_bit(check[1], 3) * 32 +
- get_bit(check[1], 1) * 16 +
- get_bit(check[0], 7) * 8 +
- get_bit(check[0], 5) * 4 +
- get_bit(check[0], 3) * 2 +
- get_bit(check[0], 1);
- col = get_bit(check[2], 7) * 4 +
- get_bit(check[2], 5) * 2 +
- get_bit(check[2], 3);
- debugn(3, "error in line: %d , col %d\n", line, col);
- debugn(3, "defect byte is: %02x\n", data[line]);
+ debugn(0, "correctable error detected ... fixing the bit\n");
+ line =
+ GET_BIT(check[1], 7) * 128 +
+ GET_BIT(check[1], 5) * 64 +
+ GET_BIT(check[1], 3) * 32 +
+ GET_BIT(check[1], 1) * 16 +
+ GET_BIT(check[0], 7) * 8 +
+ GET_BIT(check[0], 5) * 4 +
+ GET_BIT(check[0], 3) * 2 +
+ GET_BIT(check[0], 1);
+ col =
+ GET_BIT(check[2], 7) * 4 +
+ GET_BIT(check[2], 5) * 2 +
+ GET_BIT(check[2], 3);
+ debugn(3, "error in line: %d , col %d (byte is: %02x)\n",
+ line, col, data[line]);
data[line] ^= ( 1 << col);
- debugn(3, "fixed byte is: %02x\n", data[line]);
+ debugn(3, "fixed byte is: %02x\n", data[line]);
} else {
- debugn(2, "uncorrectable error detected. Sorry you lose!\n");
+ debugn(0, "uncorrectable error detected. Sorry, you lose!\n");
return 1;
}
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 07:48:44 +0000