[Qemu-devel] [PATCH v14 05/13] Add uleb encoding/decoding functions

[Orit Wasserman <owasserm@redhat.com>]

Implement Unsigned Little Endian Base 128.

Signed-off-by: Orit Wasserman <owasserm@redhat.com>
---
 cutils.c      |   32 ++++++++++++++++++++++++++++++++
 qemu-common.h |    8 ++++++++
 2 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/cutils.c b/cutils.c
index af308cd..3f81d53 100644
--- a/cutils.c
+++ b/cutils.c
@@ -549,3 +549,35 @@ int qemu_sendv(int sockfd, struct iovec *iov, int len, int iov_offset)
     return do_sendv_recvv(sockfd, iov, len, iov_offset, 1);
 }
 
+/*
+ * Implementation of  ULEB128 (http://en.wikipedia.org/wiki/LEB128)
+ * Input is limited to 14-bit numbers
+ */
+int uleb128_encode_small(uint8_t *out, uint32_t n)
+{
+    g_assert(n <= 0x3fff);
+    if (n < 0x80) {
+        *out++ = n;
+        return 1;
+    } else {
+        *out++ = (n & 0x7f) | 0x80;
+        *out++ = n >> 7;
+        return 2;
+    }
+}
+
+int uleb128_decode_small(const uint8_t *in, uint32_t *n)
+{
+    if (!(*in & 0x80)) {
+        *n = *in++;
+        return 1;
+    } else {
+        *n = *in++ & 0x7f;
+        /* we exceed 14 bit number */
+        if (*in & 0x80) {
+            return -1;
+        }
+        *n |= *in++ << 7;
+        return 2;
+    }
+}
diff --git a/qemu-common.h b/qemu-common.h
index 1ce7023..42e4498 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -437,4 +437,12 @@ static inline int64_t round2pow2(int64_t value)
 
 #include "module.h"
 
+/*
+ * Implementation of ULEB128 (http://en.wikipedia.org/wiki/LEB128)
+ * Input is limited to 14-bit numbers
+ */
+
+int uleb128_encode_small(uint8_t *out, uint32_t n);
+int uleb128_decode_small(const uint8_t *in, uint32_t *n);
+
 #endif
-- 
1.7.7.6