From: Amaury Denoyelle <adenoyelle@haproxy.com>
Date: Thu, 16 Oct 2025 15:34:10 +0000 (+0200)
Subject: MINOR: ncbuf2: implement iterator bitmap utilities functions
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=99e54fa962647154357dd287a368401dac7cbfeb;p=thirdparty%2Fhaproxy.git

MINOR: ncbuf2: implement iterator bitmap utilities functions
---

diff --git a/src/ncbuf2.c b/src/ncbuf2.c
index ba83ce8b2..0cea43d01 100644
--- a/src/ncbuf2.c
+++ b/src/ncbuf2.c
@@ -2,6 +2,87 @@
 
 #include <string.h>
 
+/* ******** internal API ******** */
+
+struct itbmap {
+	char *b;
+	ncb2_sz_t off;
+	unsigned char mask;
+	unsigned char bitcount;
+};
+
+static int itbmap_is_full(const struct itbmap *it)
+{
+	if (!it->b)
+		return 0;
+
+	return (*it->b & it->mask) == it->mask;
+}
+
+static void itbmap_load(struct itbmap *it, ncb2_sz_t off,
+                         const struct ncbuf2 *buf)
+{
+	const ncb2_sz_t sz = ncb2_size(buf);
+	ncb2_sz_t off_abs;
+	ncb2_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;
+	}
+}
+
+static struct itbmap itbmap_get(const struct ncbuf2 *buf, ncb2_sz_t off)
+{
+	struct itbmap it;
+
+	BUG_ON(off >= ncb2_size(buf));
+
+	itbmap_load(&it, off, buf);
+	return it;
+}
+
+static struct itbmap itbmap_next(const struct ncbuf2 *buf, const struct itbmap *prev)
+{
+	const ncb2_sz_t off_next = prev->off + prev->bitcount;
+	struct itbmap next;
+
+	BUG_ON_HOT(off_next > ncb2_size(buf));
+
+	if (off_next == ncb2_size(buf)) {
+		next.b = NULL;
+		next.off = off_next;
+	}
+	else {
+		itbmap_load(&next, prev->off + prev->bitcount, buf);
+	}
+
+	return next;
+}
+
+/* ******** public API ******** */
+
 struct ncbuf2 ncb2_make(char *area, ncb2_sz_t size, ncb2_sz_t head)
 {
 	struct ncbuf2 buf;