1 files changed, 174 insertions, 0 deletions
diff --git a/newstr.c b/newstr.c
new file mode 100644
index 0000000..6a229eb
--- /dev/null
+++ b/newstr.c
@@ -0,0 +1,174 @@
+/*
+ * 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 ); */
+}