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| author | Ronald G. Minnich <rminnich@gmail.com> | 2013-01-30 14:29:34 -0800 |
|---|---|---|
| committer | David Hendricks <dhendrix@chromium.org> | 2013-01-31 23:18:16 +0100 |
| commit | 79e36d90608a929c33b655c6fb6376f33f332e6f (patch) | |
| tree | 185114440365b321d96e7643564a42debc1edb9d | |
| parent | bc3abbbaf05123f87cee143845868bf6b95fdd3e (diff) | |
| download | coreboot-79e36d90608a929c33b655c6fb6376f33f332e6f.tar.xz | |
Improve how our printk calls do_div by using constants.
The do_div code has a nice optimization in it when it is called with
constants. The current highly generalized use of it defeats those
optimizations and causes trouble on ARM, resulting in a complex and
buggy code path.
Since we only need to print in bases 8, 10, and 16, do a minor
restructuring of the code so that we call do_div with constants.
If you need base 2, print in base 16 and do it in your head. :-)
This fixes an ongoing problem with ARM, will not harm X86, and will
help PPC should we ever want to support it again.
Plus, I don't have to ever try to understand the div64 assembly and where
it's going wrong :-)
Change-Id: I6a480011916eb0834e05c5bb10909d83330fe797
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-on: http://review.coreboot.org/2235
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
| -rw-r--r-- | src/console/vtxprintf.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/src/console/vtxprintf.c b/src/console/vtxprintf.c index 28c5a604e0..9de25845bd 100644 --- a/src/console/vtxprintf.c +++ b/src/console/vtxprintf.c @@ -69,8 +69,22 @@ static int number(void (*tx_byte)(unsigned char byte), i = 0; if (num == 0) tmp[i++]='0'; - else while (num != 0) - tmp[i++] = digits[do_div(num,base)]; + else while (num != 0){ + /* there are some nice optimizations in the + * Macros-From-Hell that form the div64 code + * *IF* you call it with a constant. + * We're firmware, we only do bases + * 8, 10, and 16. Let's be smart. + * This greatly helps ARM, reduces the + * code footprint at compile time, and does not hurt x86. + */ + if (base == 10) + tmp[i++] = digits[do_div(num,10)]; + else if (base == 8) + tmp[i++] = digits[do_div(num,8)]; + else /* sorry, you're out of choices */ + tmp[i++] = digits[do_div(num,16)]; + } if (i > precision) precision = i; size -= precision; |