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winhelp: Implement generic B+ tree search function.

This commit is contained in:
Kirill K. Smirnov 2007-12-01 19:00:24 +03:00 committed by Alexandre Julliard
parent bef9ab5dd5
commit 6e002c59ce
1 changed files with 74 additions and 0 deletions
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74
programs/winhelp/hlpfile.c
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@ -75,6 +75,18 @@ static struct
HLPFILE_LINK* link;
} attributes;
/*
* Compare function type for HLPFILE_BPTreeSearch function.
*
* PARAMS
* p [I] pointer to testing block (key + data)
* key [I] pointer to key value to look for
* leaf [I] whether this function called for index of leaf page
* next [O] pointer to pointer to next block
*/
typedef int (*HLPFILE_BPTreeCompare)(void *p, const void *key,
int leaf, void **next);
static BOOL HLPFILE_DoReadHlpFile(HLPFILE*, LPCSTR);
static BOOL HLPFILE_ReadFileToBuffer(HFILE);
static BOOL HLPFILE_FindSubFile(LPCSTR name, BYTE**, BYTE**);
@ -93,6 +105,8 @@ static BOOL HLPFILE_Uncompress3(char*, const char*, const BYTE*, const BYTE*);
static void HLPFILE_UncompressRLE(const BYTE* src, const BYTE* end, BYTE** dst, unsigned dstsz);
static BOOL HLPFILE_ReadFont(HLPFILE* hlpfile);
static void* HLPFILE_BPTreeSearch(BYTE*, const void*, HLPFILE_BPTreeCompare);
/***********************************************************************
*
* HLPFILE_PageByNumber
@ -1904,6 +1918,66 @@ static void HLPFILE_UncompressRLE(const BYTE* src, const BYTE* end, BYTE** dst,
*dst - (sdst - dstsz), dstsz);
}
/**************************************************************************
* HLPFILE_BPTreeSearch
*
* Searches for an element in B+ tree
*
* PARAMS
* buf [I] pointer to the embedded file structured as a B+ tree
* key [I] pointer to data to find
* comp [I] compare function
*
* RETURNS
* Pointer to block identified by key, or NULL if failure.
*
*/
static void* HLPFILE_BPTreeSearch(BYTE* buf, const void* key,
HLPFILE_BPTreeCompare comp)
{
unsigned magic;
unsigned page_size;
unsigned cur_page;
unsigned level;
BYTE *pages, *ptr, *newptr;
int i, entries;
int ret;
magic = GET_USHORT(buf, 9);
if (magic != 0x293B)
{
WINE_ERR("Invalid magic in B+ tree: 0x%x\n", magic);
return NULL;
}
page_size = GET_USHORT(buf, 9+4);
cur_page = GET_USHORT(buf, 9+26);
level = GET_USHORT(buf, 9+32);
pages = buf + 9 + 38;
while (--level > 0)
{
ptr = pages + cur_page*page_size;
entries = GET_SHORT(ptr, 2);
ptr += 6;
for (i = 0; i < entries; i++)
{
if (comp(ptr, key, 0, (void **)&newptr) > 0) break;
ptr = newptr;
}
cur_page = GET_USHORT(ptr-2, 0);
}
ptr = pages + cur_page*page_size;
entries = GET_SHORT(ptr, 2);
ptr += 8;
for (i = 0; i < entries; i++)
{
ret = comp(ptr, key, 1, (void **)&newptr);
if (ret == 0) return ptr;
if (ret > 0) return NULL;
ptr = newptr;
}
return NULL;
}
/******************************************************************
* HLPFILE_EnumBTreeLeaves
*