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authorKenneth Heafield <github@kheafield.com>2012-05-12 14:01:52 -0400
committerKenneth Heafield <github@kheafield.com>2012-05-12 14:01:52 -0400
commit3faecf9a00512dcbc8712c4bca9adae72fb64410 (patch)
tree9761b50d12f81a675fb7cbc663ceebad15079f78 /jam-files/engine/newstr.c
parentc806a8fff63043f63773874986301f2822a2b552 (diff)
Give in and copy bjam into cdec source code
Diffstat (limited to 'jam-files/engine/newstr.c')
-rw-r--r--jam-files/engine/newstr.c174
1 files changed, 174 insertions, 0 deletions
diff --git a/jam-files/engine/newstr.c b/jam-files/engine/newstr.c
new file mode 100644
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+++ b/jam-files/engine/newstr.c
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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 ); */
+}