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package rtcp
// getPadding Returns the padding required to make the length a multiple of 4
func getPadding(len int) int {
if len%4 == 0 {
return 0
}
return 4 - (len % 4)
}
// setNBitsOfUint16 will truncate the value to size, left-shift to startIndex position and set
func setNBitsOfUint16(src, size, startIndex, val uint16) (uint16, error) {
if startIndex+size > 16 {
return 0, errInvalidSizeOrStartIndex
}
// truncate val to size bits
val &= (1 << size) - 1
return src | (val << (16 - size - startIndex)), nil
}
// appendBit32 will left-shift and append n bits of val
func appendNBitsToUint32(src, n, val uint32) uint32 {
return (src << n) | (val & (0xFFFFFFFF >> (32 - n)))
}
// getNBit get n bits from 1 byte, begin with a position
func getNBitsFromByte(b byte, begin, n uint16) uint16 {
endShift := 8 - (begin + n)
mask := (0xFF >> begin) & uint8(0xFF<<endShift)
return uint16(b&mask) >> endShift
}
// get24BitFromBytes get 24bits from `[3]byte` slice
func get24BitsFromBytes(b []byte) uint32 {
return uint32(b[0])<<16 + uint32(b[1])<<8 + uint32(b[2])
}
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