This commit factors the ability to write ordinary EBML numbers out of
the functions for writing EBML lengths. This is in preparation for
future commits.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
---
libavformat/matroskaenc.c | 36 ++++++++++++++++++++++++++----------
1 file changed, 26 insertions(+), 10 deletions(-)
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 7cea813dc0..92cd819312 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -190,19 +190,38 @@ static void put_ebml_size_unknown(AVIOContext *pb, int
bytes)
}
/**
- * Calculate how many bytes are needed to represent the length field
- * of an EBML element whose payload has a given length.
+ * Returns how many bytes are needed to represent a number
+ * as EBML variable length integer.
*/
-static int ebml_length_size(uint64_t length)
+static int ebml_num_size(uint64_t num)
{
int bytes = 0;
- length++;
do {
bytes++;
- } while (length >>= 7);
+ } while (num >>= 7);
return bytes;
}
+/**
+ * Calculate how many bytes are needed to represent the length field
+ * of an EBML element whose payload has a given length.
+ */
+static int ebml_length_size(uint64_t length)
+{
+ return ebml_num_size(length + 1);
+}
+
+/**
+ * Write a number as EBML variable length integer on `bytes` bytes.
+ * `bytes` is taken literally without checking.
+ */
+static void put_ebml_num(AVIOContext *pb, uint64_t num, int bytes)
+{
+ num |= 1ULL << bytes * 7;
+ for (int i = bytes - 1; i >= 0; i--)
+ avio_w8(pb, (uint8_t)(num >> i * 8));
+}
+
/**
* Write a length as EBML variable length integer.
*
@@ -211,7 +230,7 @@ static int ebml_length_size(uint64_t length)
*/
static void put_ebml_length(AVIOContext *pb, uint64_t length, int bytes)
{
- int i, needed_bytes = ebml_length_size(length);
+ int needed_bytes = ebml_length_size(length);
// sizes larger than this are currently undefined in EBML
av_assert0(length < (1ULL << 56) - 1);
@@ -221,10 +240,7 @@ static void put_ebml_length(AVIOContext *pb, uint64_t
length, int bytes)
// The bytes needed to write the given size must not exceed
// the bytes that we ought to use.
av_assert0(bytes >= needed_bytes);
-
- length |= 1ULL << bytes * 7;
- for (i = bytes - 1; i >= 0; i--)
- avio_w8(pb, (uint8_t)(length >> i * 8));
+ put_ebml_num(pb, length, bytes);
}
/**
--
2.20.1
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