/*
* Allocate a GDT slot as follows:
* 1) If there are entries on the free list, use those.
* 2) If there are fewer than gdt_size entries in use, there are free slots
* near the end that we can sweep through.
* 3) As a last resort, we increase the size of the GDT, and sweep through
* the new slots.
*/
int
gdt_get_slot()
{
int slot;
gdt_lock();
if (gdt_free != GNULL_SEL) {
slot = gdt_free;
gdt_free = dynamic_gdt[slot].gd.gd_selector;
} else {
if (gdt_next != gdt_count)
panic("gdt_get_slot: gdt_next != gdt_count");
if (gdt_next >= gdt_size) {
if (gdt_size >= MAXGDTSIZ)
panic("gdt_get_slot: out of GDT descriptors");
if (dynamic_gdt == gdt)
panic("gdt_get_slot called before gdt_init");
gdt_grow();
}
slot = gdt_next++;
}
gdt_count++;
gdt_unlock();
return (slot);
}
int
gdt_get_slot1(int which)
{
int slot;
size_t offset;
gdt_lock();
if (gdt_free[which] != GNULL_SEL) {
slot = gdt_free[which];
gdt_free[which] = gdt[slot].gd.gd_selector;
} else {
offset = which * MAXGDTSIZ * sizeof(gdt[0]);
if (gdt_next[which] != gdt_count[which] + offset)
panic("gdt_get_slot botch 1");
if (gdt_next[which] - offset >= gdt_size[which]) {
if (gdt_size[which] >= MAXGDTSIZ)
panic("gdt_get_slot botch 2");
gdt_grow(which);
}
slot = gdt_next[which]++;
}
gdt_count[which]++;
gdt_unlock();
return (slot);
}
int
gdt_get_slot1(int which)
{
size_t offset;
int slot;
gdt_lock();
if (gdt_free[which] != GNULL_SEL) {
slot = gdt_free[which];
gdt_free[which] = gdt[slot].gd.gd_selector;
} else {
offset = which * MAXGDTSIZ * sizeof(gdt[0]);
if (gdt_next[which] != gdt_count[which] + offset)
panic("gdt_get_slot1: gdt_next[%d] != gdt_count[%d]",
which, which);
if (gdt_next[which] >= gdt_size[which]) {
if (gdt_size[which] >= MAXGDTSIZ)
panic("gdt_get_slot1: out of GDT descriptors");
gdt_grow(which);
}
slot = gdt_next[which]++;
}
gdt_count[which]++;
gdt_unlock();
return (slot);
}
