Add efficient bit-fields manipulations.

Signed-off-by: Pierre Habouzit <madcoder@debian.org>

diff --git a/lib-lib/CMakeLists.txt b/lib-lib/CMakeLists.txt
index b8af186..2a6e031 100644 (file)
--- a/lib-lib/CMakeLists.txt
+++ b/lib-lib/CMakeLists.txt
@@ -1,14 +1,15 @@
 ADD_LIBRARY(lib
-    str.c
-    md5.c
-    utf8.c
+    array.c
+    bits.c
     buffer.c
+    date.c
+    file.c
     hash.c
-    array.c
     list.c
-    file.c
     mapping.c
-    date.c
+    md5.c
     rx.c
+    str.c
     url.c
+    utf8.c
 )

diff --git a/lib-lib/bits.c b/lib-lib/bits.c
new file mode 100644 (file)
index 0000000..1cd09ef
--- /dev/null
+++ b/lib-lib/bits.c
@@ -0,0 +1,48 @@
+/*
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or (at
+ *  your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ *  MA 02110-1301, USA.
+ */
+/*
+ * Copyright © 2007 Pierre Habouzit
+ */
+
+#include "lib-lib.h"
+
+#define UPPER_32(x)  (((x) + 31) & ~31)
+#define LOWER_32(x)  ((x) & ~31)
+
+void bits_extend(bits_t *bits, int pos)
+{
+    if (bits->size == 0) {
+        bits->start = LOWER_32(pos >> 3);
+    }
+
+    if (pos >> 3 > bits->start + bits->size) {
+        int newsize = UPPER_32((pos >> 3) - bits->start + 1);
+        p_realloc(&bits->bits, bits->size = newsize);
+        return;
+    }
+
+    if (pos >> 3 < bits->start) {
+        unsigned char *tmp = bits->bits;
+        int prepend = LOWER_32(bits->start - (pos >> 3));
+
+        bits->bits   = p_new(unsigned char, bits->size + prepend);
+        memcpy(bits->bits + prepend, tmp, bits->size);
+        bits->size  += prepend;
+        bits->start -= prepend;
+        p_delete(&tmp);
+    }
+}

diff --git a/lib-lib/bits.h b/lib-lib/bits.h
new file mode 100644 (file)
index 0000000..499189b
--- /dev/null
+++ b/lib-lib/bits.h
@@ -0,0 +1,83 @@
+/*
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or (at
+ *  your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ *  MA 02110-1301, USA.
+ */
+/*
+ * Copyright © 2007 Pierre Habouzit
+ */
+
+#ifndef MUTT_LIB_LIB_BITS_H
+#define MUTT_LIB_LIB_BITS_H
+
+typedef struct bits_t {
+    int start;
+    int size;
+    unsigned char *bits;
+} bits_t;
+
+void bits_extend(bits_t *bits, int pos);
+
+DO_INIT(bits_t, bits);
+static inline void bits_wipe(bits_t *bits) {
+    p_delete(&bits->bits);
+}
+DO_NEW(bits_t, bits);
+DO_DELETE(bits_t, bits);
+
+static inline void bits_clear(bits_t *bits)
+{
+    bits_wipe(bits);
+    bits_init(bits);
+}
+
+static inline bool bit_isset(const bits_t *bits, int pos)
+{
+    int offs = (pos >> 3) - bits->start;
+    if (offs < 0 || offs > bits->size)
+        return false;
+
+    return (bits->bits[offs] & (1 << (pos & 7))) != 0;
+}
+
+static inline void bit_set(bits_t *bits, int pos)
+{
+    int offs = (pos >> 3) - bits->start;
+    if (offs < 0 || offs > bits->size) {
+        bits_extend(bits, pos);
+        offs = (pos >> 3) - bits->start;
+    }
+    bits->bits[offs] |= 1 << (pos & 7);
+}
+
+static inline void bit_clear(bits_t *bits, int pos)
+{
+    int offs = (pos >> 3) - bits->start;
+    if (offs < 0 || offs > bits->size)
+        return;
+    bits->bits[offs] &= ~(1 << (pos & 7));
+}
+
+static inline void bit_toggle(bits_t *bits, int pos)
+{
+    int offs = (pos >> 3) - bits->start;
+    if (offs < 0 || offs > bits->size) {
+        bits_extend(bits, pos);
+        offs = (pos >> 3) - bits->start;
+    }
+    bits->bits[offs] ^= 1 << (pos & 7);
+}
+
+
+#endif /* MUTT_LIB_LIB_BITS_H */

diff --git a/lib-lib/lib-lib.h b/lib-lib/lib-lib.h
index c254e95..edee99b 100644 (file)
--- a/lib-lib/lib-lib.h
+++ b/lib-lib/lib-lib.h
@@ -58,6 +58,7 @@
 #elif HAVE_INTTYPES_H
 # include <inttypes.h>
 #endif
+#include <stdbool.h>
 
 #ifdef HAVE_SYS_TIME_H
 # include <sys/time.h>
@@ -113,6 +114,7 @@ typedef union __attribute__((transparent_union)) anytype {
 #include "utf8.h"
 
 #include "array.h"
+#include "bits.h"
 #include "buffer.h"
 #include "date.h"
 #include "file.h"