Aren/haiku
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Refined cv_factor calculation.

Browse Source 
Also set TIMER_CLKNUM_HZ to its correct value.


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@418 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
notion 2002-07-24 12:39:31 +00:00
parent 7a89b5cb9e
commit 719e338bae
1 changed files with 11 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/kernel/boot/arch/x86/stage2.c
View File

@ -497,7 +497,7 @@ sleep(uint64 time)
_v; \
})
#define TIMER_CLKNUM_HZ 1193167
#define TIMER_CLKNUM_HZ (14318180/12)
static void
calculate_cpu_conversion_factor(void)
@ -610,7 +610,7 @@ not_so_quick_sample:
* where reminder is:
*
* floor((1<<k)*decimalPart((C*x0)/p3))
*
*
* which is approximated as:
*
* floor((1<<k)*decimalPart(((C*x0)%p3)/p3)) ->
@ -619,10 +619,13 @@ not_so_quick_sample:
* So the final expression is:
*
* ((C*x0)/p3)<<k + (((C*x0)%p3)<<k)/p3 + (C*x1)/p3
*
* Just to make things fancier we choose k based on the input
* parameters (we use log2(expired)/3.)
*
*/
/*
* To get the highest accuracy with this method
* x0 should have the 12 most significant bits of expired
* to minimize the error upon <<k.
*/
/*
* Of course, you are not expected to understand any of this.
*/
{
@ -635,11 +638,10 @@ not_so_quick_sample:
/* first calculate k*/
k = 0;
for (i = 0; i< 32; i++) {
for (i = 12; i < 16; i++) {
if (expired & (1<<i))
k = i;
k = i - 11;
}
k /= 3;
C = 1000000ULL << 32;
x0 = expired >> k;