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Fix and simplify usage map handling

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whydoubt
2004-08-18 04:18:24 +00:00
parent f2125dd3bc
commit 1f30522bd0
2 changed files with 35 additions and 45 deletions
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3
ChangeLog
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@@ -1,3 +1,6 @@
Tue Aug 17 22:46:13 CDT 2004 Jeff Smith <whydoubt@yahoo.com>
* src/libmdb/data.c: Fix and simplify usage map handling
Wed Aug 4 21:22:46 CDT 2004 Jeff Smith <whydoubt@yahoo.com>
* HACKING:
* include/mdbtools.h:

77
src/libmdb/data.c
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@@ -434,37 +434,37 @@ static int _mdb_attempt_bind(MdbHandle *mdb,
}
return 1;
}
int
mdb_read_next_dpg_by_map0(MdbTableDef *table)
static int
mdb_read_next_dpg0(MdbTableDef *table)
{
MdbCatalogEntry *entry = table->entry;
MdbHandle *mdb = entry->mdb;
unsigned int pgnum, i, bitn;
unsigned int pgnum, i;
unsigned char *usage_bitmap;
unsigned int usage_bitlen;
pgnum = mdb_get_int32(table->usage_map,1);
/* the first 5 bytes of the usage map mean something */
for (i=5;i<table->map_sz;i++) {
for (bitn=0;bitn<8;bitn++) {
if (table->usage_map[i] & 1 << bitn && pgnum > table->cur_phys_pg) {
table->cur_phys_pg = pgnum;
if (!mdb_read_pg(mdb, pgnum)) {
return 0;
} else {
return pgnum;
}
}
pgnum++;
usage_bitmap = table->usage_map + 5;
usage_bitlen = (table->map_sz - 5) * 8;
for (i=table->cur_phys_pg-pgnum+1; i<usage_bitlen; i++) {
if (usage_bitmap[i/8] & (1 << (i%8))) {
table->cur_phys_pg = pgnum + i;
return (mdb_read_pg(mdb, table->cur_phys_pg))
? table->cur_phys_pg : 0;
}
}
/* didn't find anything */
return 0;
}
int
mdb_read_next_dpg_by_map1(MdbTableDef *table)
static int
mdb_read_next_dpg1(MdbTableDef *table)
{
MdbCatalogEntry *entry = table->entry;
MdbHandle *mdb = entry->mdb;
guint32 pgnum, i, j, bitn, map_pg, map_ind, offset, bit_offset;
guint32 i, map_pg, map_ind, max_map_pgs, offset;
unsigned char *usage_bitmap;
unsigned int usage_bitlen = (mdb->fmt->pg_size - 4) * 8;
/*
* table->cur_phys_pg will tell us where to (re)start the scan
@@ -475,19 +475,17 @@ mdb_read_next_dpg_by_map1(MdbTableDef *table)
* offset gives us a page offset into the bitmap (must be converted
* to bytes and bits).
*/
pgnum = table->cur_phys_pg + 1;
map_ind = pgnum / ((mdb->fmt->pg_size - 4) * 8);
offset = pgnum % ((mdb->fmt->pg_size - 4) * 8);
bit_offset = offset % 8;
max_map_pgs = (table->map_sz - 1) / 4;
map_ind = (table->cur_phys_pg + 1) / usage_bitlen;
offset = (table->cur_phys_pg + 1) % usage_bitlen;
//printf("map size %ld\n", table->map_sz);
for (i = 4 * map_ind + 1;i < table->map_sz-1; i += 4) {
map_pg = mdb_get_int32(table->usage_map, i);
for (; map_ind<max_map_pgs; map_ind++) {
map_pg = mdb_get_int32(table->usage_map, (map_ind*4)+1);
//printf("loop %d pg %ld %02x%02x%02x%02x\n",i, map_pg,table->usage_map[i],table->usage_map[i+1],table->usage_map[i+2],table->usage_map[i+3]);
/* if the usage_map entry is empty, skip it, but advance the page counter */
/* if the usage_map entry is empty, skip it */
if (!map_pg) {
pgnum += (mdb->fmt->pg_size - 4) * 8;
continue;
}
@@ -498,24 +496,13 @@ mdb_read_next_dpg_by_map1(MdbTableDef *table)
//printf("reading page %ld\n",map_pg);
/* first time through, start j, bitn based on the starting offset
* after that, reset offset to 0 to start at the beginning of the page/byte
*/
for (j=4 + offset;j<mdb->fmt->pg_size;j++) {
for (bitn=bit_offset;bitn<8;bitn++) {
if (mdb->alt_pg_buf[j] & 1 << bitn && pgnum > table->cur_phys_pg) {
table->cur_phys_pg = pgnum;
if (!mdb_read_pg(mdb, pgnum)) {
return 0;
} else {
//printf("page found at %04x %d\n",pgnum, pgnum);
return pgnum;
}
}
pgnum++;
usage_bitmap = mdb->alt_pg_buf + 4;
for (i=offset; i<usage_bitlen; i++) {
if (usage_bitmap[i/8] & (1 << (i%8))) {
table->cur_phys_pg = map_ind*usage_bitlen + i;
return (mdb_read_pg(mdb, table->cur_phys_pg))
? table->cur_phys_pg : 0;
}
bit_offset = 0;
}
offset = 0;
}
@@ -534,11 +521,11 @@ guint32 pg;
#ifndef SLOW_READ
map_type = table->usage_map[0];
if (map_type==0) {
pg = mdb_read_next_dpg_by_map0(table);
pg = mdb_read_next_dpg0(table);
//printf("Next dpg = %lu\n", pg);
return pg;
} else if (map_type==1) {
pg = mdb_read_next_dpg_by_map1(table);
pg = mdb_read_next_dpg1(table);
//printf("Next dpg = %lu\n", pg);
return pg;
} else {