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SubjectRe: [PATCH v2 4/5] kdb: Improve handling of characters from different input sources
Hi,

On Tue, Oct 8, 2019 at 6:21 AM Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> Currently if an escape timer is interrupted by a character from a
> different input source then the new character is discarded and the
> function returns '\e' (which will be discarded by the level above).
> It is hard to see why this would ever be the desired behaviour.

I guess the 2nd input source would be if you enable keyboard input?
Personally I've never used this myself, but your functional change
seems OK to me.


> Fix this to return the new character rather then the '\e'.

s/then/than


> This is a bigger refactor that might be expected because the new
> character needs to go through escape sequence detection.
>
> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
> ---
> kernel/debug/kdb/kdb_io.c | 37 ++++++++++++++++++-------------------
> 1 file changed, 18 insertions(+), 19 deletions(-)
>
> diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
> index a9e73bc9d1c3..288dd1babf90 100644
> --- a/kernel/debug/kdb/kdb_io.c
> +++ b/kernel/debug/kdb/kdb_io.c
> @@ -122,8 +122,8 @@ static int kdb_getchar(void)
> {
> #define ESCAPE_UDELAY 1000
> #define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
> - char escape_data[5]; /* longest vt100 escape sequence is 4 bytes */
> - char *ped = escape_data;
> + char buf[4]; /* longest vt100 escape sequence is 4 bytes */
> + char *pbuf = buf;
> int escape_delay = 0;
> get_char_func *f, *f_escape = NULL;
> int key;
> @@ -145,27 +145,26 @@ static int kdb_getchar(void)
> continue;
> }
>
> - if (escape_delay == 0 && key == '\e') {
> - escape_delay = ESCAPE_DELAY;
> - ped = escape_data;
> + /*
> + * When the first character is received (or we get a change
> + * input source) we set ourselves up to handle an escape
> + * sequences (just in case).
> + */
> + if (f_escape != f) {
> f_escape = f;

Would it make sense to rename "f_escape" to "f_last" or "f_prev" now?
Essentially this logic now happens every time you change input
sources.


-Doug

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