patch-2.4.1 linux/fs/reiserfs/hashes.c

• Lines: 227
• Date: Mon Jan 15 12:42:32 2001
• Orig file: v2.4.0/linux/fs/reiserfs/hashes.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.0/linux/fs/reiserfs/hashes.c linux/fs/reiserfs/hashes.c
@@ -0,0 +1,226 @@
+
+/*
+ * Keyed 32-bit hash function using TEA in a Davis-Meyer function
+ *   H0 = Key
+ *   Hi = E Mi(Hi-1) + Hi-1
+ *
+ * (see Applied Cryptography, 2nd edition, p448).
+ *
+ * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998
+ * 
+ * Jeremy has agreed to the contents of reiserfs/README. -Hans
+ * Yura's function is added (04/07/2000)
+ */
+
+//
+// keyed_hash
+// yura_hash
+// r5_hash
+//
+
+#include <asm/types.h>
+
+
+
+#define DELTA 0x9E3779B9
+#define FULLROUNDS 10		/* 32 is overkill, 16 is strong crypto */
+#define PARTROUNDS 6		/* 6 gets complete mixing */
+
+#ifndef __KERNEL__
+typedef __u32 u32;
+#endif
+
+/* a, b, c, d - data; h0, h1 - accumulated hash */
+#define TEACORE(rounds)							\
+	do {								\
+		u32 sum = 0;						\
+		int n = rounds;						\
+		u32 b0, b1;						\
+									\
+		b0 = h0;						\
+		b1 = h1;						\
+									\
+		do							\
+		{							\
+			sum += DELTA;					\
+			b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);	\
+			b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);	\
+		} while(--n);						\
+									\
+		h0 += b0;						\
+		h1 += b1;						\
+	} while(0)
+
+
+u32 keyed_hash(const char *msg, int len)
+{
+	u32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3}; 
+
+	u32 h0 = k[0], h1 = k[1];
+	u32 a, b, c, d;
+	u32 pad;
+	int i;
+ 
+
+	//	assert(len >= 0 && len < 256);
+
+	pad = (u32)len | ((u32)len << 8);
+	pad |= pad << 16;
+
+	while(len >= 16)
+	{
+		a = (u32)msg[ 0]      |
+		    (u32)msg[ 1] << 8 |
+		    (u32)msg[ 2] << 16|
+		    (u32)msg[ 3] << 24;
+		b = (u32)msg[ 4]      |
+		    (u32)msg[ 5] << 8 |
+		    (u32)msg[ 6] << 16|
+		    (u32)msg[ 7] << 24;
+		c = (u32)msg[ 8]      |
+		    (u32)msg[ 9] << 8 |
+		    (u32)msg[10] << 16|
+		    (u32)msg[11] << 24;
+		d = (u32)msg[12]      |
+		    (u32)msg[13] << 8 |
+		    (u32)msg[14] << 16|
+		    (u32)msg[15] << 24;
+		
+		TEACORE(PARTROUNDS);
+
+		len -= 16;
+		msg += 16;
+	}
+
+	if (len >= 12)
+	{
+	    	//assert(len < 16);
+		if (len >= 16)
+		    *(int *)0 = 0;
+
+		a = (u32)msg[ 0]      |
+		    (u32)msg[ 1] << 8 |
+		    (u32)msg[ 2] << 16|
+		    (u32)msg[ 3] << 24;
+		b = (u32)msg[ 4]      |
+		    (u32)msg[ 5] << 8 |
+		    (u32)msg[ 6] << 16|
+		    (u32)msg[ 7] << 24;
+		c = (u32)msg[ 8]      |
+		    (u32)msg[ 9] << 8 |
+		    (u32)msg[10] << 16|
+		    (u32)msg[11] << 24;
+
+		d = pad;
+		for(i = 12; i < len; i++)
+		{
+			d <<= 8;
+			d |= msg[i];
+		}
+	}
+	else if (len >= 8)
+	{
+	    	//assert(len < 12);
+		if (len >= 12)
+		    *(int *)0 = 0;
+		a = (u32)msg[ 0]      |
+		    (u32)msg[ 1] << 8 |
+		    (u32)msg[ 2] << 16|
+		    (u32)msg[ 3] << 24;
+		b = (u32)msg[ 4]      |
+		    (u32)msg[ 5] << 8 |
+		    (u32)msg[ 6] << 16|
+		    (u32)msg[ 7] << 24;
+
+		c = d = pad;
+		for(i = 8; i < len; i++)
+		{
+			c <<= 8;
+			c |= msg[i];
+		}
+	}
+	else if (len >= 4)
+	{
+	    	//assert(len < 8);
+		if (len >= 8)
+		    *(int *)0 = 0;
+		a = (u32)msg[ 0]      |
+		    (u32)msg[ 1] << 8 |
+		    (u32)msg[ 2] << 16|
+		    (u32)msg[ 3] << 24;
+
+		b = c = d = pad;
+		for(i = 4; i < len; i++)
+		{
+			b <<= 8;
+			b |= msg[i];
+		}
+	}
+	else
+	{
+	    	//assert(len < 4);
+		if (len >= 4)
+		    *(int *)0 = 0;
+		a = b = c = d = pad;
+		for(i = 0; i < len; i++)
+		{
+			a <<= 8;
+			a |= msg[i];
+		}
+	}
+
+	TEACORE(FULLROUNDS);
+
+/*	return 0;*/
+	return h0^h1;
+}
+
+/* What follows in this file is copyright 2000 by Hans Reiser, and the
+ * licensing of what follows is governed by reiserfs/README */
+
+u32 yura_hash (const char *msg, int len)
+{
+    int j, pow;
+    u32 a, c;
+    int i;
+    
+    for (pow=1,i=1; i < len; i++) pow = pow * 10; 
+    
+    if (len == 1) 
+	a = msg[0]-48;
+    else
+	a = (msg[0] - 48) * pow;
+    
+    for (i=1; i < len; i++) {
+	c = msg[i] - 48; 
+	for (pow=1,j=i; j < len-1; j++) pow = pow * 10; 
+	a = a + c * pow;
+    }
+    
+    for (; i < 40; i++) {
+	c = '0' - 48; 
+	for (pow=1,j=i; j < len-1; j++) pow = pow * 10; 
+	a = a + c * pow;
+    }
+    
+    for (; i < 256; i++) {
+	c = i; 
+	for (pow=1,j=i; j < len-1; j++) pow = pow * 10; 
+	a = a + c * pow;
+    }
+    
+    a = a << 7;
+    return a;
+}
+
+u32 r5_hash (const char *msg, int len)
+{
+  u32 a=0;
+  while(*msg) { 
+    a += *msg << 4;
+    a += *msg >> 4;
+    a *= 11;
+    msg++;
+   } 
+  return a;
+}