On Tue, Feb 21, 2017 at 05:48:19PM +0100, walter harms wrote:
> >
>
> XSyncValueSubtract is doing as expected,
> XSyncValue is the simulation of 64bitvalues on 32bit.
> see this in hex:
> 100000001
> -000000002
> 0FFFFFFFF = 4294967295 in .lo
>
Kind of - it errorneously returns
1 0000 0001
-0 0000 0002
1 ffff ffff
Test source attached.
I.e.
XSyncValueSubtract should handle the .lo becoming <0,
and it checks only for .lo_after_subtract < .lo,
which would only be aplicable to uint.
E.g. there is a typo in XSyncValue.lo definition - it should be uint
instead.
Also in ServertimeBlockHandler, "timeout" is unsigned,
while it is get from signed .lo and used as signed arg to
AdjustWaitForTimeout.
Perhaps also:
AdjustWaitForTimeout should not be used if overflow != 0
Because something is wrong then as (pnext_time < Now) ?
Mihail
#include <stdio.h>
#include <stdint.h>
typedef int Bool;
struct xtime {
int32_t hi;
int32_t lo;
};
struct utime {
int32_t hi;
uint32_t lo; /* uint vs. int doesn't seem to matter, in XSyncValueSubtract too */
};
void print_xtime(char *comment, struct xtime *x, Bool in_hex) {
printf("%s: { hi=%d lo=%d }\n", comment, x->hi, x->lo);
if (in_hex) {
printf("%s: { hi=%x lo=%x }\n", comment, x->hi, x->lo);
}
}
void print_utime(char *comment, struct utime *x, Bool in_hex) {
printf("%s: { hi=%d lo=%u }\n", comment, x->hi, x->lo);
if (in_hex) {
printf("%s: { hi=%x lo=%x }\n", comment, x->hi, x->lo);
}
}
void set_xtime(struct xtime *x, int hi, int lo) {
x->hi = hi;
x->lo = lo;
}
void set_utime(struct utime *x, int hi, int lo) {
x->hi = hi;
x->lo = lo;
}
#define XSyncValueIsNegative(v) (((v).hi & 0x80000000) ? 1 : 0)
#define _XSyncValueSubtract(presult,a,b,poverflow) {\
int t = (a).lo;\
Bool signa = XSyncValueIsNegative(a);\
Bool signb = XSyncValueIsNegative(b);\
((presult)->lo = (a).lo - (b).lo);\
((presult)->hi = (a).hi - (b).hi);\
if (t<(presult)->lo) (presult)->hi--;\
*poverflow = ((signa == signb) && !(signa == XSyncValueIsNegative(*presult)));\
}
#define FixedXSyncValueSubtract(presult,a,b,poverflow) {\
uint32_t t = (a).lo;\
Bool signa = XSyncValueIsNegative(a);\
Bool signb = XSyncValueIsNegative(b);\
((presult)->lo = (a).lo - (b).lo);\
((presult)->hi = (a).hi - (b).hi);\
if (t<(presult)->lo || (presult)->lo < 0) (presult)->hi--;\
*poverflow = ((signa == signb) && !(signa == XSyncValueIsNegative(*presult)));\
}
void test_subtract(int a_hi, int a_lo, int b_hi, int b_lo) {
int overflow;
struct xtime d, a, b;
struct utime ud, ua, ub;
set_xtime(&a, a_hi, a_lo);
set_xtime(&b, b_hi, b_lo);
print_xtime("a", &a, 0);
print_xtime("b", &b, 0);
_XSyncValueSubtract(&d, a, b, &overflow);
print_xtime("a-b", &d, 1);
printf("a-b overflow: %c\n", (overflow ? 'y' : 'n'));
set_utime(&ua, a_hi, a_lo);
set_utime(&ub, b_hi, b_lo);
FixedXSyncValueSubtract(&ud, ua, ub, &overflow);
print_utime("fixed a-b", &ud, 1);
printf("fixed a-b overflow: %c\n", (overflow ? 'y' : 'n'));
printf("\n");
}
int main(int argc, char **argv) {
test_subtract(2, 2, 1, 4);
test_subtract(2, 2, 4, 0);
test_subtract(1, 1, 0, 2);
return 0;
}
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