Introduce spaceship comparison for Processes

If currently two unsigned values are compared via `a - b`, in the case b
is actually bigger than a, the result will not be an negative number (as
-1 is expected) but a huge positive number as the subtraction is an
unsigned subtraction.

Avoid over-/underflow affected operations; use comparisons.
Modern compilers will generate sane code, like:
    xor     eax, eax
    cmp     rdi, rsi
    seta    al
    sbb     eax, 0
    ret
This commit is contained in:
Christian Göttsche
2020-11-04 17:46:24 +01:00
committed by BenBE
parent d785b1bbc3
commit 397b5c4bd0
7 changed files with 111 additions and 84 deletions

View File

@ -110,6 +110,7 @@ void DragonFlyBSDProcess_writeField(const Process* this, RichString* str, Proces
long DragonFlyBSDProcess_compare(const void* v1, const void* v2) {
const DragonFlyBSDProcess *p1, *p2;
const Settings *settings = ((const Process*)v1)->settings;
if (settings->direction == 1) {
p1 = (const DragonFlyBSDProcess*)v1;
p2 = (const DragonFlyBSDProcess*)v2;
@ -117,12 +118,13 @@ long DragonFlyBSDProcess_compare(const void* v1, const void* v2) {
p2 = (const DragonFlyBSDProcess*)v1;
p1 = (const DragonFlyBSDProcess*)v2;
}
switch ((int) settings->sortKey) {
// add Platform-specific fields here
case JID:
return (p1->jid - p2->jid);
return SPACESHIP_NUMBER(p1->jid, p2->jid);
case JAIL:
return strcmp(p1->jname ? p1->jname : "", p2->jname ? p2->jname : "");
return SPACESHIP_NULLSTR(p1->jname, p2->jname);
default:
return Process_compare(v1, v2);
}