From 9c1c5cb60113ddfd555a83c8e6768a8a95c1e867 Mon Sep 17 00:00:00 2001
From: Jake Lane <me@jakelane.me>
Date: Fri, 20 Jul 2018 10:23:40 +0930
Subject: [PATCH] rtmp: Implemented afmEncodeInt24

---
 rtmp/rtmp.go | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/rtmp/rtmp.go b/rtmp/rtmp.go
index 6c0c9894..76a8adf5 100644
--- a/rtmp/rtmp.go
+++ b/rtmp/rtmp.go
@@ -793,12 +793,11 @@ func sendPacket(r *C.RTMP, packet *C.RTMPPacket, queue int) int {
 		if t > 0xffffff {
 			res = 0xffffff
 		}
-		hptr = unsafe.Pointer(C.AMF_EncodeInt24((*C.char)(hptr), (*C.char)(hend), C.int(res)))
+		hptr = unsafe.Pointer(afmEncodeInt24((*byte)(hptr), (*byte)(hend), res))
 	}
 
 	if nSize > 4 {
-		hptr = unsafe.Pointer(C.AMF_EncodeInt24((*C.char)(hptr), (*C.char)(hend),
-			C.int(packet.m_nBodySize)))
+		hptr = unsafe.Pointer(afmEncodeInt24((*byte)(hptr), (*byte)(hend), (int32(packet.m_nBodySize))))
 		*(*byte)(hptr) = byte(packet.m_packetType)
 		hptr = incBytePtr(hptr, 1)
 	}
@@ -962,6 +961,29 @@ func afmDecodeInt16(data *byte) uint16 {
 	return (uint16(*(*uint8)(c)) << 8) | *(*uint16)(incBytePtr(c, 1))
 }
 
+// afmEncodeInt24 encodes a int24 into data
+func afmEncodeInt24(output *byte, outend *byte, nVal int32) *byte {
+	outputPtr := unsafe.Pointer(output)
+	outendPtr := unsafe.Pointer(outend)
+	if uintptr(outputPtr)+3 > uintptr(outendPtr) {
+		// length < 3
+		return nil
+	}
+
+	// Assign output[2]
+	third := (*byte)(incBytePtr(outputPtr, 2))
+	*third = (byte)(nVal & 0xff)
+
+	// Assign output[1]
+	second := (*byte)(incBytePtr(outputPtr, 1))
+	*second = (byte)(nVal >> 8)
+
+	// Assign output[0]
+	*output = (byte)(nVal >> 16)
+
+	return (*byte)(incBytePtr(outputPtr, 3))
+}
+
 func writeN(r *C.RTMP, buffer unsafe.Pointer, n int) int {
 	ptr := buffer
 	for n > 0 {