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extracted general methods to zip.c for reuse in other zip* structures

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This commit is contained in:
Pieter Noordhuis 2010-05-21 12:53:34 +02:00
parent d55d5c5dd3
commit 3d04d29e7f
2 changed files with 80 additions and 75 deletions
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46
zip.c Normal file
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@ -0,0 +1,46 @@
#define ZIP_BIGLEN 254
#define ZIP_END 255
/* The following macro returns the number of bytes needed to encode the length
* for the integer value _l, that is, 1 byte for lengths < ZIP_BIGLEN and
* 5 bytes for all the other lengths. */
#define ZIP_LEN_BYTES(_l) (((_l) < ZIP_BIGLEN) ? 1 : sizeof(unsigned int)+1)
/* Decode the encoded length pointed by 'p' */
static unsigned int zipDecodeLength(unsigned char *p) {
unsigned int len = *p;
if (len < ZIP_BIGLEN) return len;
memcpy(&len,p+1,sizeof(unsigned int));
return len;
}
/* Encode the length 'l' writing it in 'p'. If p is NULL it just returns
* the amount of bytes required to encode such a length. */
static unsigned int zipEncodeLength(unsigned char *p, unsigned int len) {
if (p == NULL) {
return ZIP_LEN_BYTES(len);
} else {
if (len < ZIP_BIGLEN) {
p[0] = len;
return 1;
} else {
p[0] = ZIP_BIGLEN;
memcpy(p+1,&len,sizeof(len));
return 1+sizeof(len);
}
}
}
/* Return the total amount used by an entry (encoded length + payload). */
static unsigned int zipRawEntryLength(unsigned char *p) {
unsigned int l = zipDecodeLength(p);
return zipEncodeLength(NULL,l) + l;
}
/* Resize the zip* structure. */
static unsigned char *zipResize(unsigned char *z, unsigned int len) {
z = zrealloc(z,len);
z[len-1] = ZIP_END;
return z;
}

109
zipmap.c
View File

@ -80,54 +80,21 @@
#include <string.h> #include <string.h>
#include <assert.h> #include <assert.h>
#include "zmalloc.h" #include "zmalloc.h"
#include "zip.c"
#define ZIPMAP_BIGLEN 254
#define ZIPMAP_END 255
/* The following defines the max value for the <free> field described in the /* The following defines the max value for the <free> field described in the
* comments above, that is, the max number of trailing bytes in a value. */ * comments above, that is, the max number of trailing bytes in a value. */
#define ZIPMAP_VALUE_MAX_FREE 4 #define ZIPMAP_VALUE_MAX_FREE 4
/* The following macro returns the number of bytes needed to encode the length
* for the integer value _l, that is, 1 byte for lengths < ZIPMAP_BIGLEN and
* 5 bytes for all the other lengths. */
#define ZIPMAP_LEN_BYTES(_l) (((_l) < ZIPMAP_BIGLEN) ? 1 : sizeof(unsigned int)+1)
/* Create a new empty zipmap. */ /* Create a new empty zipmap. */
unsigned char *zipmapNew(void) { unsigned char *zipmapNew(void) {
unsigned char *zm = zmalloc(2); unsigned char *zm = zmalloc(2);
zm[0] = 0; /* Length */ zm[0] = 0; /* Length */
zm[1] = ZIPMAP_END; zm[1] = ZIP_END;
return zm; return zm;
} }
/* Decode the encoded length pointed by 'p' */
static unsigned int zipmapDecodeLength(unsigned char *p) {
unsigned int len = *p;
if (len < ZIPMAP_BIGLEN) return len;
memcpy(&len,p+1,sizeof(unsigned int));
return len;
}
/* Encode the length 'l' writing it in 'p'. If p is NULL it just returns
* the amount of bytes required to encode such a length. */
static unsigned int zipmapEncodeLength(unsigned char *p, unsigned int len) {
if (p == NULL) {
return ZIPMAP_LEN_BYTES(len);
} else {
if (len < ZIPMAP_BIGLEN) {
p[0] = len;
return 1;
} else {
p[0] = ZIPMAP_BIGLEN;
memcpy(p+1,&len,sizeof(len));
return 1+sizeof(len);
}
}
}
/* Search for a matching key, returning a pointer to the entry inside the /* Search for a matching key, returning a pointer to the entry inside the
* zipmap. Returns NULL if the key is not found. * zipmap. Returns NULL if the key is not found.
* *
@ -138,12 +105,12 @@ static unsigned char *zipmapLookupRaw(unsigned char *zm, unsigned char *key, uns
unsigned char *p = zm+1, *k = NULL; unsigned char *p = zm+1, *k = NULL;
unsigned int l,llen; unsigned int l,llen;
while(*p != ZIPMAP_END) { while(*p != ZIP_END) {
unsigned char free; unsigned char free;
/* Match or skip the key */ /* Match or skip the key */
l = zipmapDecodeLength(p); l = zipDecodeLength(p);
llen = zipmapEncodeLength(NULL,l); llen = zipEncodeLength(NULL,l);
if (k == NULL && l == klen && !memcmp(p+llen,key,l)) { if (k == NULL && l == klen && !memcmp(p+llen,key,l)) {
/* Only return when the user doesn't care /* Only return when the user doesn't care
* for the total length of the zipmap. */ * for the total length of the zipmap. */
@ -155,8 +122,8 @@ static unsigned char *zipmapLookupRaw(unsigned char *zm, unsigned char *key, uns
} }
p += llen+l; p += llen+l;
/* Skip the value as well */ /* Skip the value as well */
l = zipmapDecodeLength(p); l = zipDecodeLength(p);
p += zipmapEncodeLength(NULL,l); p += zipEncodeLength(NULL,l);
free = p[0]; free = p[0];
p += l+1+free; /* +1 to skip the free byte */ p += l+1+free; /* +1 to skip the free byte */
} }
@ -168,25 +135,23 @@ static unsigned long zipmapRequiredLength(unsigned int klen, unsigned int vlen)
unsigned int l; unsigned int l;
l = klen+vlen+3; l = klen+vlen+3;
if (klen >= ZIPMAP_BIGLEN) l += 4; if (klen >= ZIP_BIGLEN) l += 4;
if (vlen >= ZIPMAP_BIGLEN) l += 4; if (vlen >= ZIP_BIGLEN) l += 4;
return l; return l;
} }
/* Return the total amount used by a key (encoded length + payload) */ /* Return the total amount used by a key (encoded length + payload) */
static unsigned int zipmapRawKeyLength(unsigned char *p) { static unsigned int zipmapRawKeyLength(unsigned char *p) {
unsigned int l = zipmapDecodeLength(p); return zipRawEntryLength(p);
return zipmapEncodeLength(NULL,l) + l;
} }
/* Return the total amount used by a value /* Return the total amount used by a value
* (encoded length + single byte free count + payload) */ * (encoded length + single byte free count + payload) */
static unsigned int zipmapRawValueLength(unsigned char *p) { static unsigned int zipmapRawValueLength(unsigned char *p) {
unsigned int l = zipmapDecodeLength(p); unsigned int l = zipDecodeLength(p);
unsigned int used; unsigned int used;
used = zipmapEncodeLength(NULL,l); used = zipEncodeLength(NULL,l);
used += p[used] + 1 + l; used += p[used] + 1 + l;
return used; return used;
} }
@ -199,12 +164,6 @@ static unsigned int zipmapRawEntryLength(unsigned char *p) {
return l + zipmapRawValueLength(p+l); return l + zipmapRawValueLength(p+l);
} }
static inline unsigned char *zipmapResize(unsigned char *zm, unsigned int len) {
zm = zrealloc(zm, len);
zm[len-1] = ZIPMAP_END;
return zm;
}
/* Set key to value, creating the key if it does not already exist. /* Set key to value, creating the key if it does not already exist.
* If 'update' is not NULL, *update is set to 1 if the key was * If 'update' is not NULL, *update is set to 1 if the key was
* already preset, otherwise to 0. */ * already preset, otherwise to 0. */
@ -219,12 +178,12 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
p = zipmapLookupRaw(zm,key,klen,&zmlen); p = zipmapLookupRaw(zm,key,klen,&zmlen);
if (p == NULL) { if (p == NULL) {
/* Key not found: enlarge */ /* Key not found: enlarge */
zm = zipmapResize(zm, zmlen+reqlen); zm = zipResize(zm, zmlen+reqlen);
p = zm+zmlen-1; p = zm+zmlen-1;
zmlen = zmlen+reqlen; zmlen = zmlen+reqlen;
/* Increase zipmap length (this is an insert) */ /* Increase zipmap length (this is an insert) */
if (zm[0] < ZIPMAP_BIGLEN) zm[0]++; if (zm[0] < ZIP_BIGLEN) zm[0]++;
} else { } else {
/* Key found. Is there enough space for the new value? */ /* Key found. Is there enough space for the new value? */
/* Compute the total length: */ /* Compute the total length: */
@ -235,7 +194,7 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
* it can be resized. Then, move the tail backwards so this * it can be resized. Then, move the tail backwards so this
* pair fits at the current position. */ * pair fits at the current position. */
offset = p-zm; offset = p-zm;
zm = zipmapResize(zm, zmlen-freelen+reqlen); zm = zipResize(zm, zmlen-freelen+reqlen);
p = zm+offset; p = zm+offset;
/* The +1 in the number of bytes to be moved is caused by the /* The +1 in the number of bytes to be moved is caused by the
@ -257,7 +216,7 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
offset = p-zm; offset = p-zm;
memmove(p+reqlen, p+freelen, zmlen-(offset+freelen+1)); memmove(p+reqlen, p+freelen, zmlen-(offset+freelen+1));
zmlen -= empty; zmlen -= empty;
zm = zipmapResize(zm, zmlen); zm = zipResize(zm, zmlen);
p = zm+offset; p = zm+offset;
vempty = 0; vempty = 0;
} else { } else {
@ -266,11 +225,11 @@ unsigned char *zipmapSet(unsigned char *zm, unsigned char *key, unsigned int kle
/* Just write the key + value and we are done. */ /* Just write the key + value and we are done. */
/* Key: */ /* Key: */
p += zipmapEncodeLength(p,klen); p += zipEncodeLength(p,klen);
memcpy(p,key,klen); memcpy(p,key,klen);
p += klen; p += klen;
/* Value: */ /* Value: */
p += zipmapEncodeLength(p,vlen); p += zipEncodeLength(p,vlen);
*p++ = vempty; *p++ = vempty;
memcpy(p,val,vlen); memcpy(p,val,vlen);
return zm; return zm;
@ -284,10 +243,10 @@ unsigned char *zipmapDel(unsigned char *zm, unsigned char *key, unsigned int kle
if (p) { if (p) {
freelen = zipmapRawEntryLength(p); freelen = zipmapRawEntryLength(p);
memmove(p, p+freelen, zmlen-((p-zm)+freelen+1)); memmove(p, p+freelen, zmlen-((p-zm)+freelen+1));
zm = zipmapResize(zm, zmlen-freelen); zm = zipResize(zm, zmlen-freelen);
/* Decrease zipmap length */ /* Decrease zipmap length */
if (zm[0] < ZIPMAP_BIGLEN) zm[0]--; if (zm[0] < ZIP_BIGLEN) zm[0]--;
if (deleted) *deleted = 1; if (deleted) *deleted = 1;
} else { } else {
@ -313,17 +272,17 @@ unsigned char *zipmapRewind(unsigned char *zm) {
* } * }
*/ */
unsigned char *zipmapNext(unsigned char *zm, unsigned char **key, unsigned int *klen, unsigned char **value, unsigned int *vlen) { unsigned char *zipmapNext(unsigned char *zm, unsigned char **key, unsigned int *klen, unsigned char **value, unsigned int *vlen) {
if (zm[0] == ZIPMAP_END) return NULL; if (zm[0] == ZIP_END) return NULL;
if (key) { if (key) {
*key = zm; *key = zm;
*klen = zipmapDecodeLength(zm); *klen = zipDecodeLength(zm);
*key += ZIPMAP_LEN_BYTES(*klen); *key += ZIP_LEN_BYTES(*klen);
} }
zm += zipmapRawKeyLength(zm); zm += zipmapRawKeyLength(zm);
if (value) { if (value) {
*value = zm+1; *value = zm+1;
*vlen = zipmapDecodeLength(zm); *vlen = zipDecodeLength(zm);
*value += ZIPMAP_LEN_BYTES(*vlen); *value += ZIP_LEN_BYTES(*vlen);
} }
zm += zipmapRawValueLength(zm); zm += zipmapRawValueLength(zm);
return zm; return zm;
@ -336,8 +295,8 @@ int zipmapGet(unsigned char *zm, unsigned char *key, unsigned int klen, unsigned
if ((p = zipmapLookupRaw(zm,key,klen,NULL)) == NULL) return 0; if ((p = zipmapLookupRaw(zm,key,klen,NULL)) == NULL) return 0;
p += zipmapRawKeyLength(p); p += zipmapRawKeyLength(p);
*vlen = zipmapDecodeLength(p); *vlen = zipDecodeLength(p);
*value = p + ZIPMAP_LEN_BYTES(*vlen) + 1; *value = p + ZIP_LEN_BYTES(*vlen) + 1;
return 1; return 1;
} }
@ -349,14 +308,14 @@ int zipmapExists(unsigned char *zm, unsigned char *key, unsigned int klen) {
/* Return the number of entries inside a zipmap */ /* Return the number of entries inside a zipmap */
unsigned int zipmapLen(unsigned char *zm) { unsigned int zipmapLen(unsigned char *zm) {
unsigned int len = 0; unsigned int len = 0;
if (zm[0] < ZIPMAP_BIGLEN) { if (zm[0] < ZIP_BIGLEN) {
len = zm[0]; len = zm[0];
} else { } else {
unsigned char *p = zipmapRewind(zm); unsigned char *p = zipmapRewind(zm);
while((p = zipmapNext(p,NULL,NULL,NULL,NULL)) != NULL) len++; while((p = zipmapNext(p,NULL,NULL,NULL,NULL)) != NULL) len++;
/* Re-store length if small enough */ /* Re-store length if small enough */
if (len < ZIPMAP_BIGLEN) zm[0] = len; if (len < ZIP_BIGLEN) zm[0] = len;
} }
return len; return len;
} }
@ -366,21 +325,21 @@ void zipmapRepr(unsigned char *p) {
printf("{status %u}",*p++); printf("{status %u}",*p++);
while(1) { while(1) {
if (p[0] == ZIPMAP_END) { if (p[0] == ZIP_END) {
printf("{end}"); printf("{end}");
break; break;
} else { } else {
unsigned char e; unsigned char e;
l = zipmapDecodeLength(p); l = zipDecodeLength(p);
printf("{key %u}",l); printf("{key %u}",l);
p += zipmapEncodeLength(NULL,l); p += zipEncodeLength(NULL,l);
fwrite(p,l,1,stdout); fwrite(p,l,1,stdout);
p += l; p += l;
l = zipmapDecodeLength(p); l = zipDecodeLength(p);
printf("{value %u}",l); printf("{value %u}",l);
p += zipmapEncodeLength(NULL,l); p += zipEncodeLength(NULL,l);
e = *p++; e = *p++;
fwrite(p,l,1,stdout); fwrite(p,l,1,stdout);
p += l+e; p += l+e;