30 Aug
2011
30 Aug
'11
11:37 a.m.
Hi Wolfgang,
On 30/08/11 19:29, Wolfgang Denk wrote:
Dear Graeme Russ,
In message CALButC+t=OUL9XgQnfyAdZmgPJRp7mdRwEE9LKogYHEg1D+m4g@mail.gmail.com you wrote:
If you want to support arbitrary buffer sizes, then just use
#define CIRC_BUF_IDX(idx) ((idx) % CONFIG_SYS_TMP_CON_BUF_SZ)I know, but I was concerned that you wouldn't like the use of modulo arithmetic for every putc() - But I suppose thats cheaper than a compare plus branch...
Well, the difference of "i & (CONFIG_SYS_TMP_CON_BUF_SZ-1)" versus "i % CONFIG_SYS_TMP_CON_BUF_SZ" is 1 versus 4 assembler instructions on Power, and 2 versus 5 assembler instructions on ARM. I think we can tolerate this.
And it's only hit during printf() before console is initialised :)
Respinning now
Regards,
Graeme