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/* No copyright?!
**
** $FreeBSD$
*/
#include <sys/queue.h>
#include "doscmd.h"
/*
** Callbacks are used for chaining interrupt handlers
** off interrupt vectors
*/
struct callback {
LIST_ENTRY(callback) chain;
u_long vec;
callback_t func;
const char *name;
};
LIST_HEAD(cbhead , callback) cbhead[127];
#define CBHASH(x) (((x) * 17) % 127)
/*
** Register (func) as a handler for (vec)
*/
void
register_callback(u_long vec, callback_t func, const char *name)
{
struct cbhead *head;
struct callback *elm;
elm = malloc(sizeof(struct callback));
elm->vec = vec;
elm->func = func;
elm->name = name;
head = &cbhead[CBHASH(vec)];
LIST_INSERT_HEAD(head, elm, chain);
}
/*
** Find a handler for (vec)
*/
callback_t
find_callback(u_long vec)
{
struct cbhead *head;
struct callback *elm;
head = &cbhead[CBHASH(vec)];
LIST_FOREACH(elm, head, chain)
if (elm->vec == vec)
break;
if (elm) {
debug(D_TRAPS2, "callback %s\n", elm->name);
return (elm->func);
} else
return ((callback_t)0);
}
u_long trampoline_rover = 0xF1000000;
/*
* Interrupts are disabled on an INTn call, so we must restore interrupts
* before via STI returning. IRET is not used here because 1) some DOS
* calls want to return status via the FLAGS register, and 2) external
* routines which hook INTn calls do not always put a FLAGS image on the
* stack which re-enables interrupts.
*/
u_char softint_trampoline[] = {
0xf4, /* HLT */
0xfb, /* STI */
0xca, /* RETF 2 */
2,
0,
};
u_char hardint_trampoline[] = {
0xf4, /* HLT */
0xcf, /* IRET */
};
u_char null_trampoline[] = {
0xcf, /* IRET */
};
u_long
insert_generic_trampoline(size_t len, u_char *p)
{
u_char *q;
u_long where;
where = trampoline_rover;
q = (u_char *)VECPTR(where);
memcpy(q, p, len);
trampoline_rover += len;
return (where);
}
u_long
insert_softint_trampoline(void)
{
return (insert_generic_trampoline(
sizeof(softint_trampoline), softint_trampoline));
}
u_long
insert_hardint_trampoline(void)
{
return (insert_generic_trampoline(
sizeof(hardint_trampoline), hardint_trampoline));
}
u_long
insert_null_trampoline(void)
{
return (insert_generic_trampoline(
sizeof(null_trampoline), null_trampoline));
}
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