From: Amaury Denoyelle <adenoyelle@haproxy.com>
Date: Thu, 16 Oct 2025 15:34:10 +0000 (+0200)
Subject: MINOR: ncbmbuf: implement iterator bitmap utilities functions
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=95d40940cdf5198fd72dd74fc40566cd1aabc121;p=thirdparty%2Fhaproxy.git

MINOR: ncbmbuf: implement iterator bitmap utilities functions
---

diff --git a/include/haproxy/ncbmbuf-t.h b/include/haproxy/ncbmbuf-t.h
index 518a3ffe4..5975e0b1c 100644
--- a/include/haproxy/ncbmbuf-t.h
+++ b/include/haproxy/ncbmbuf-t.h
@@ -23,6 +23,7 @@ struct ncbmbuf {
 	char *area;
 	char *bitmap;
 	ncb_sz_t size;
+	ncb_sz_t bitmap_sz;
 	ncb_sz_t head;
 };
 
diff --git a/src/ncbmbuf.c b/src/ncbmbuf.c
index 8cb61b8a4..5f51b1217 100644
--- a/src/ncbmbuf.c
+++ b/src/ncbmbuf.c
@@ -2,6 +2,105 @@
 
 #include <string.h>
 
+#ifdef DEBUG_STRICT
+# include <haproxy/bug.h>
+#else
+# include <stdio.h>
+# include <stdlib.h>
+
+# undef  BUG_ON
+# define BUG_ON(x)     if (x) { fprintf(stderr, "CRASH ON %s:%d\n", __func__, __LINE__); abort(); }
+
+# undef  BUG_ON_HOT
+# define BUG_ON_HOT(x) if (x) { fprintf(stderr, "CRASH ON %s:%d\n", __func__, __LINE__); abort(); }
+#endif /* DEBUG_STRICT */
+
+/* ******** internal API ******** */
+
+/* Type representing a bitmap byte. */
+struct itbmap {
+	char *b;
+	ncb_sz_t off;
+	unsigned char mask;
+	unsigned char bitcount;
+};
+
+static __attribute__((unused)) int itbmap_is_full(const struct itbmap *it)
+{
+	if (!it->b)
+		return 0;
+
+	return (*it->b & it->mask) == it->mask;
+}
+
+static __attribute__((unused)) void itbmap_load(struct itbmap *it, ncb_sz_t off,
+                                                const struct ncbmbuf *buf)
+{
+	const ncb_sz_t sz = ncbmb_size(buf);
+	ncb_sz_t off_abs;
+	ncb_sz_t off_bmap;
+
+	off_abs = buf->head + off;
+	if (off_abs >= sz)
+		off_abs -= sz;
+	off_bmap = off_abs / 8;
+	BUG_ON_HOT(off_bmap >= buf->bitmap_sz);
+
+	it->b = buf->bitmap + off_bmap;
+	it->off = off;
+	it->mask = 0xff;
+	it->bitcount = 8;
+
+	if (off_bmap == buf->bitmap_sz - 1 && (sz % 8)) {
+		it->mask <<= 8 - (sz % 8);
+		it->bitcount -= 8 - (sz % 8);
+	}
+
+	if (off_abs % 8) {
+		it->mask &= (0xff >> (off_abs % 8));
+		it->bitcount -= off_abs % 8;
+	}
+
+	if (it->off + it->bitcount > sz) {
+		it->mask &= (0xff << (it->off + it->bitcount - sz));
+		it->bitcount -= it->off + it->bitcount - sz;
+	}
+}
+
+/* Returns an iterator on the bitmap byte corresponding to <off> offset
+ * relative to <buf> head.
+ */
+static __attribute__((unused)) struct itbmap itbmap_get(const struct ncbmbuf *buf, ncb_sz_t off)
+{
+	struct itbmap it;
+
+	BUG_ON(off >= ncbmb_size(buf));
+
+	itbmap_load(&it, off, buf);
+	return it;
+}
+
+/* Returns the next bitmap byte relative to <prev> iterator. */
+static __attribute__((unused)) struct itbmap itbmap_next(const struct ncbmbuf *buf, const struct itbmap *prev)
+{
+	const ncb_sz_t off_next = prev->off + prev->bitcount;
+	struct itbmap next;
+
+	BUG_ON_HOT(off_next > ncbmb_size(buf));
+
+	if (off_next == ncbmb_size(buf)) {
+		next.b = NULL;
+		next.off = off_next;
+	}
+	else {
+		itbmap_load(&next, prev->off + prev->bitcount, buf);
+	}
+
+	return next;
+}
+
+/* ******** public API ******** */
+
 /* Construct a ncbmbuf with all its parameters. */
 struct ncbmbuf ncbmb_make(char *area, ncb_sz_t size, ncb_sz_t head)
 {