diff options
Diffstat (limited to 'sys/isa/atrtc.c')
| -rw-r--r-- | sys/isa/atrtc.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/sys/isa/atrtc.c b/sys/isa/atrtc.c index c865514fdcb0..95bef69e2715 100644 --- a/sys/isa/atrtc.c +++ b/sys/isa/atrtc.c @@ -34,7 +34,7 @@ * SUCH DAMAGE. * * from: @(#)clock.c 7.2 (Berkeley) 5/12/91 - * $Id: clock.c,v 1.28 1994/11/12 16:24:54 ache Exp $ + * $Id: clock.c,v 1.29 1994/12/30 12:43:34 bde Exp $ */ /* @@ -292,9 +292,30 @@ calibrate_cyclecounter(void) * This assumes that you will never have a clock rate higher * than 4GHz, probably a good assumption. */ - cycles_per_sec = (long long)edx + eax; - cycles_per_sec -= (long long)lastedx + lasteax; + /* The following C code is correct, but our current gcc 2.6.3 + * seems to produce bad assembly code for it , ATS , XXXX */ +#if 0 + cycles_per_sec = ((long long)edx << 32) + eax; + cycles_per_sec -= ((long long)lastedx << 32) + lasteax; pentium_mhz = ((long)cycles_per_sec + 500000) / 1000000; /* round up */ +#else + /* produce a workaround for the code above */ + { + union { + long long extralong; + long shorty[2]; + } tmp; + + tmp.shorty[0] = eax; + tmp.shorty[1] = edx; + cycles_per_sec = tmp.extralong; + tmp.shorty[0] = lasteax; + tmp.shorty[1] = lastedx; + cycles_per_sec -= tmp.extralong; + /* round up */ + pentium_mhz = (long) ((cycles_per_sec + 500000) / 1000000); + } +#endif } #endif |