On 29/03/14 16:11, David Härdeman wrote:
> Using the full 32 bits for all kinds of NEC scancodes simplifies rc-core
> and the nec decoder without any loss of functionality.
>
> In order to maintain backwards compatibility, some heuristics are added
> in rc-main.c to convert scancodes to NEC32 as necessary.
>
> I plan to introduce a different ioctl later which makes the protocol
> explicit (and which expects all NEC scancodes to be 32 bit, thereby
> removing the need for guesswork).
>
> Signed-off-by: David Härdeman <david@xxxxxxxxxxx>
> ---
> diff --git a/drivers/media/rc/img-ir/img-ir-nec.c b/drivers/media/rc/img-ir/img-ir-nec.c
> index 40ee844..133ea45 100644
> --- a/drivers/media/rc/img-ir/img-ir-nec.c
> +++ b/drivers/media/rc/img-ir/img-ir-nec.c
> @@ -5,42 +5,20 @@
> */
>
> #include "img-ir-hw.h"
> -#include <linux/bitrev.h>
>
> /* Convert NEC data to a scancode */
> static int img_ir_nec_scancode(int len, u64 raw, enum rc_type *protocol,
> u32 *scancode, u64 enabled_protocols)
> {
> - unsigned int addr, addr_inv, data, data_inv;
> /* a repeat code has no data */
> if (!len)
> return IMG_IR_REPEATCODE;
> +
> if (len != 32)
> return -EINVAL;
> - /* raw encoding: ddDDaaAA */
> - addr = (raw >> 0) & 0xff;
> - addr_inv = (raw >> 8) & 0xff;
> - data = (raw >> 16) & 0xff;
> - data_inv = (raw >> 24) & 0xff;
> - if ((data_inv ^ data) != 0xff) {
> - /* 32-bit NEC (used by Apple and TiVo remotes) */
> - /* scan encoding: AAaaDDdd (LSBit first) */
> - *scancode = bitrev8(addr) << 24 |
> - bitrev8(addr_inv) << 16 |
> - bitrev8(data) << 8 |
> - bitrev8(data_inv);
> - } else if ((addr_inv ^ addr) != 0xff) {
> - /* Extended NEC */
> - /* scan encoding: AAaaDD */
> - *scancode = addr << 16 |
> - addr_inv << 8 |
> - data;
> - } else {
> - /* Normal NEC */
> - /* scan encoding: AADD */
> - *scancode = addr << 8 |
> - data;
> - }
> +
> + /* raw encoding : ddDDaaAA -> scan encoding: AAaaDDdd */
> + *scancode = swab32((u32)raw);
What's the point of the byte swapping?
Surely the most natural NEC encoding would just treat it as a single
32-bit (LSBit first) field rather than 4 8-bit fields that needs swapping.
Cheers
James
Attachment:
signature.asc
Description: OpenPGP digital signature
