Dear Graeme Russ,
In message
<CALButCJF1p+60WOLtiJqhcAed-71VxmP2mBqY2wdNURPk5=q...@mail.gmail.com> you wrote:
>
> >> > it's fairly easy as well:
> >> > #define CIRC_BUF_IDX(idx) ((idx) & (CONFIG_SYS_TMP_CON_BUF_SZ-1))
> >> > buffer[CIRC_BUF_IDX(gd->conf_buf_idx++)] = c;
> >>
> >> But does that work for non power-of-two buffer sizes...
> >
> > no, but not that big of a deal. so you get limited to the last 1KiB, 4KiB,
> > 8KiB, 16KiB, etc... amount of data.
>
> Until someone doesn't read the documentation and figures they can only
> squeeze 200 bytes out of their L1 cache after making room for gd and stack
> and then tries to print 201 bytes of debug info and trashes either the
> stack or gd and then things start to get a lot weirder than simply having
> their early debug messgaes clipped...
>
> To be safe, CONFIG_SYS_TMP_CON_BUF_SZ would need to be checked for ^2 size
> and now we only get 128 bytes rather than 200 :( - Better to add another
> long in gd and get 196
Grrrgh.
If you want to support arbitrary buffer sizes, then just use
#define CIRC_BUF_IDX(idx) ((idx) % CONFIG_SYS_TMP_CON_BUF_SZ)
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
Use C++ to confuse your enemies; use C to produce stable code.
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