udebug: add functions for manipulating entry length

Can be used to reserve worst case length using udebug_entry_append,
then setting the final length using udebug_entry_set_length

Signed-off-by: Felix Fietkau <nbd@nbd.name>

2 files changed, 21 insertions, 0 deletions

diff --git a/udebug.c b/udebug.c
index 5be9b54..00a66ab 100644
--- a/udebug.c
+++ b/udebug.c
@@ -467,6 +467,25 @@ void *udebug_entry_append(struct udebug_buf *buf, const void *data, uint32_t len
 	return ret;
 }
 
+uint16_t udebug_entry_trim(struct udebug_buf *buf, uint16_t len)
+{
+	struct udebug_hdr *hdr = buf->hdr;
+	struct udebug_ptr *ptr = udebug_ring_ptr(hdr, hdr->head);
+
+	if (len)
+		ptr->len -= len;
+
+	return ptr->len;
+}
+
+void udebug_entry_set_length(struct udebug_buf *buf, uint16_t len)
+{
+	struct udebug_hdr *hdr = buf->hdr;
+	struct udebug_ptr *ptr = udebug_ring_ptr(hdr, hdr->head);
+
+	ptr->len = len;
+}
+
 int udebug_entry_printf(struct udebug_buf *buf, const char *fmt, ...)
 {
 	va_list ap;
diff --git a/udebug.h b/udebug.h
index d24dbfc..75c2e3f 100644
--- a/udebug.h
+++ b/udebug.h
@@ -157,6 +157,8 @@ int udebug_entry_printf(struct udebug_buf *buf, const char *fmt, ...)
 	__attribute__ ((format (printf, 2, 3)));
 int udebug_entry_vprintf(struct udebug_buf *buf, const char *fmt, va_list ap)
 	__attribute__ ((format (printf, 2, 0)));
+uint16_t udebug_entry_trim(struct udebug_buf *buf, uint16_t len);
+void udebug_entry_set_length(struct udebug_buf *buf, uint16_t len);
 void udebug_entry_add(struct udebug_buf *buf);
 
 int udebug_buf_init(struct udebug_buf *buf, size_t entries, size_t size);