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/*
* Copyright 1993, 1995 Christopher Seiwald.
*
* This file is part of Jam - see jam.c for Copyright information.
*/
# include "jam.h"
# include "newstr.h"
# include "hash.h"
# include "compile.h"
# include <stddef.h>
# include <stdlib.h>
/*
* newstr.c - string manipulation routines
*
* To minimize string copying, string creation, copying, and freeing
* is done through newstr.
*
* External functions:
*
* newstr() - return a dynamically allocated copy of a string
* copystr() - return a copy of a string previously returned by newstr()
* freestr() - free a string returned by newstr() or copystr()
* str_done() - free string tables
*
* Once a string is passed to newstr(), the returned string is readonly.
*
* This implementation builds a hash table of all strings, so that multiple
* calls of newstr() on the same string allocate memory for the string once.
* Strings are never actually freed.
*/
typedef char * STRING;
static struct hash * strhash = 0;
static int strtotal = 0;
static int strcount_in = 0;
static int strcount_out = 0;
/*
* Immortal string allocator implementation speeds string allocation and cuts
* down on internal fragmentation.
*/
# define STRING_BLOCK 4096
typedef struct strblock
{
struct strblock * next;
char data[STRING_BLOCK];
} strblock;
static strblock * strblock_chain = 0;
/* Storage remaining in the current strblock */
static char * storage_start = 0;
static char * storage_finish = 0;
/*
* allocate() - Allocate n bytes of immortal string storage.
*/
static char * allocate( size_t const n )
{
#ifdef BJAM_NEWSTR_NO_ALLOCATE
return (char*)BJAM_MALLOC_ATOMIC(n);
#else
/* See if we can grab storage from an existing block. */
size_t remaining = storage_finish - storage_start;
if ( remaining >= n )
{
char * result = storage_start;
storage_start += n;
return result;
}
else /* Must allocate a new block. */
{
strblock * new_block;
size_t nalloc = n;
if ( nalloc < STRING_BLOCK )
nalloc = STRING_BLOCK;
/* Allocate a new block and link into the chain. */
new_block = (strblock *)BJAM_MALLOC( offsetof( strblock, data[0] ) + nalloc * sizeof( new_block->data[0] ) );
if ( new_block == 0 )
return 0;
new_block->next = strblock_chain;
strblock_chain = new_block;
/* Take future allocations out of the larger remaining space. */
if ( remaining < nalloc - n )
{
storage_start = new_block->data + n;
storage_finish = new_block->data + nalloc;
}
return new_block->data;
}
#endif
}
/*
* newstr() - return a dynamically allocated copy of a string.
*/
char * newstr( char * string )
{
STRING str;
STRING * s = &str;
if ( !strhash )
strhash = hashinit( sizeof( STRING ), "strings" );
*s = string;
if ( hashenter( strhash, (HASHDATA **)&s ) )
{
int l = strlen( string );
char * m = (char *)allocate( l + 1 );
strtotal += l + 1;
memcpy( m, string, l + 1 );
*s = m;
}
strcount_in += 1;
return *s;
}
/*
* copystr() - return a copy of a string previously returned by newstr()
*/
char * copystr( char * s )
{
strcount_in += 1;
return s;
}
/*
* freestr() - free a string returned by newstr() or copystr()
*/
void freestr( char * s )
{
strcount_out += 1;
}
/*
* str_done() - free string tables.
*/
void str_done()
{
/* Reclaim string blocks. */
while ( strblock_chain != 0 )
{
strblock * n = strblock_chain->next;
BJAM_FREE(strblock_chain);
strblock_chain = n;
}
hashdone( strhash );
if ( DEBUG_MEM )
printf( "%dK in strings\n", strtotal / 1024 );
/* printf( "--- %d strings of %d dangling\n", strcount_in-strcount_out, strcount_in ); */
}
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