strbuf: add strbuf_add_uint()
strbuf_addf() calls vsnprintf(3) underneath, which supports a plethora of formatting options. We can avoid its overhead in basic cases by providing specialized functions like strbuf_addstr() for strings. Add another one, strbuf_add_uint(), for unsigned integers. Prepare the number string in a temporary buffer. Make it big enough for any unsigned integer value: A decimal digit can represent ln(10)/ln(2) ≈ 3.32 bits; dividing the number of bits of uintmax_t by 3.3 and rounding up gives a sufficiently close conservative size estimate. Signed-off-by: René Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
René Scharfe committed
May 12, 2026 at 13:56 UTC
cdeef283bcf8529fc858cfe7d18a7522294519c4
2 files changed
+18
strbuf.c
+12
index 3e04addc22..9731ecdc1f 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -361,6 +361,18 @@ void strbuf_addf(struct strbuf *sb, const char *fmt, ...)
va_end(ap);
}
+void strbuf_add_uint(struct strbuf *sb, uintmax_t value)
+{
+ char buf[DIV_ROUND_UP(bitsizeof(value) * 10, 33)];
+ char *end = buf + sizeof(buf);
+ char *p = end;
+
+ do
+ *--p = "0123456789"[value % 10];
+ while (value /= 10);
+ strbuf_add(sb, p, end - p);
+}
+
static void add_lines(struct strbuf *out,
const char *prefix,
const char *buf, size_t size,
strbuf.h
+6
index 06e284f9cc..1089ae687b 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -410,6 +410,12 @@ void strbuf_humanise_rate(struct strbuf *buf, off_t bytes);
__attribute__((format (printf,2,3)))
void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
+
+/**
+ * Add an unsigned decimal number.
+ */
+void strbuf_add_uint(struct strbuf *sb, uintmax_t value);
+
/**
* Add a formatted string prepended by a comment character and a
* blank to the buffer.