Hi James.
On 10 February 2014 12:25, James Hogan <james.hogan@xxxxxxxxxx> wrote:
> Hi Antti,
>
> On 08/02/14 12:07, Antti Seppälä wrote:
>> Adding a simple Manchester encoder to rc-core.
>> Manchester coding is used by at least RC-5 protocol and its variants.
>>
>> Signed-off-by: Antti Seppälä <a.seppala@xxxxxxxxx>
>> ---
>> drivers/media/rc/ir-raw.c | 44 +++++++++++++++++++++++++++++++++++++++++
>> drivers/media/rc/rc-core-priv.h | 14 +++++++++++++
>> 2 files changed, 58 insertions(+)
>>
>> diff --git a/drivers/media/rc/ir-raw.c b/drivers/media/rc/ir-raw.c
>> index 9d734dd..7fea9ac 100644
>> --- a/drivers/media/rc/ir-raw.c
>> +++ b/drivers/media/rc/ir-raw.c
>> @@ -240,6 +240,50 @@ ir_raw_get_allowed_protocols(void)
>> return protocols;
>> }
>>
>> +int ir_raw_gen_manchester(struct ir_raw_event **ev, unsigned int max,
>> + const struct ir_raw_timings_manchester *timings,
>> + unsigned int n, unsigned int data)
>> +{
>> + bool need_pulse;
>> + int i, count = 0;
>> + i = 1 << (n - 1);
>> +
>> + if (n > max || max < 2)
>> + return -EINVAL;
>> +
>> + if (timings->pulse_space_start) {
>> + init_ir_raw_event_duration((*ev)++, 1, timings->clock);
>> + init_ir_raw_event_duration((*ev), 0, timings->clock);
>> + count += 2;
>> + } else {
>> + init_ir_raw_event_duration((*ev), 1, timings->clock);
>> + count++;
>> + }
>> + i >>= 1;
>
> If you use pulse_space_start to encode the first bit, did you mean to
> discard the highest bit of data?
>
I did not mean to discard data but to just start the ir pulse with
logic 1 as that first bit is discarded when decoding.
>> +
>> + while (i > 0) {
>> + if (count > max)
>
> if count > max I think you've already overflowed the buffer (max is more
> of a max count rather than max buffer index).
>
I guess you're right. I'll address this in next version of my patch.
>> + return -EINVAL;
>> +
>> + need_pulse = !(data & i);
>> + if (need_pulse == !!(*ev)->pulse) {
>> + (*ev)->duration += timings->clock;
>> + } else {
>> + init_ir_raw_event_duration(++(*ev), need_pulse,
>> + timings->clock);
>> + count++;
>
> I guess you need to check for buffer space here too.
>
This comment seems also correct. Thank you for reviewing.
>> + }
>> +
>> + init_ir_raw_event_duration(++(*ev), !need_pulse,
>> + timings->clock);
>> + count++;
>> + i >>= 1;
>> + }
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL(ir_raw_gen_manchester);
>
> Cheers
> James
>
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