A.R.Drone Developer Guide - Abstract

* Else: ⇒ Resulting value (zero-counter) is equal to the direct decimal conversion
of the merged read binary values. Ex: if xxxx = 1101(2) → 000001(2) + 1101(2) =
0000011101(2) = 29(10)
– Add "0" to the output list, as many times indicated by the zero-counter.
– Reading of the non-zero value as explain below:
* Read the coarse pattern part (bit-per-bit, till there is 1 value).
* On the corresponding line (cf.Figure 15), get the number of complementary bits
to read. Ex: 0001(2) → xxs → 2 more bits to read (then the sign bit.)
* If there is no 0 before the 1 (coarse pattern part = 1, in the first case of the Huffman
table): ⇒ Temporary value is equal to 1.
* Else if the coarse pattern part = 01(2) (second case of the Huffman table) : ⇒
Temporary value is equal to End Of Bloc code (EOB).
* Else ⇒ Temporary value is equal to the direct decimal conversion of the merged
read binary values. Ex: if xx = 11 → 00001(2) + 11(2) = 0000111(2) = 7(10) Read
the next bit, to get the sign (s).
* If s = 0: ⇒ Resulting non-zero value = temporary value
* Else (s = 1): ⇒
* Resulting non-zero value = temporary value x (-1)
– Add the resulting non-zero value to the output list.
• (End of "while")
7.2.4 Example
Encoding :
• Initial data list :
-26; -3; 0; 0; 0; 0; 7; -5; EOB
• Step 1 :
-26; 0x"0"; -3; 4x"0"; 7; 0x"0"; -5; 0x"0"; EOB
• Step 2 (binary form):
1111111111100110; 1; 001 11; 0001 00; 0001 110; 1; 0001 011; 1; 01
• Final stream :
1111100110100111000100000111010001011101
Decoding :
• Initial bit-data stream :
{11110001110111000110001010010100001010001101}
• Step 1 (first 10 bits split) :
{1111000111}; {0111000110001010010100001010001101}
• Step 2 (16-bits conversion of DC value) :
{1111111111000111}; {0111000110001010010100001010001101}
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