90c38ed200
a group of dos emulator developers. Submitted by: Jonathan Lemon <jlemon@americantv.com> Obtained from: BSDI
121 lines
2.3 KiB
C
121 lines
2.3 KiB
C
/* No copyright?!
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**
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** $Id: callback.c,v 1.3 1996/09/24 00:02:25 miff Exp $
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*/
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#include <sys/queue.h>
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#include "doscmd.h"
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/*
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** Callbacks are used for chaining interrupt handlers
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** off interrupt vectors
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*/
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struct callback {
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LIST_ENTRY(callback) chain;
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u_long vec;
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callback_t func;
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char *name;
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};
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LIST_HEAD(cbhead , callback) cbhead[127];
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#define CBHASH(x) (((x) * 17) % 127)
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/*
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** Register (func) as a handler for (vec)
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*/
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void
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register_callback(u_long vec, callback_t func, char *name)
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{
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struct cbhead *head;
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struct callback *elm;
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elm = malloc(sizeof(struct callback));
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elm->vec = vec;
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elm->func = func;
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elm->name = name;
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head = &cbhead[CBHASH(vec)];
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LIST_INSERT_HEAD(head, elm, chain);
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}
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/*
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** Find a handler for (vec)
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*/
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callback_t
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find_callback(u_long vec)
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{
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struct cbhead *head;
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struct callback *elm;
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head = &cbhead[CBHASH(vec)];
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for (elm = head->lh_first; elm; elm = elm->chain.le_next)
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if (elm->vec == vec)
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break;
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if (elm) {
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debug(D_TRAPS2, "callback %s\n", elm->name);
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return (elm->func);
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} else
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return ((callback_t)0);
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}
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u_long trampoline_rover = 0xF1000000;
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/*
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* Interrupts are disabled on an INTn call, so we must restore interrupts
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* before via STI returning. IRET is not used here because 1) some DOS
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* calls want to return status via the FLAGS register, and 2) external
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* routines which hook INTn calls do not always put a FLAGS image on the
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* stack which re-enables interrupts.
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*/
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u_char softint_trampoline[] = {
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0xf4, /* HLT */
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0xfb, /* STI */
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0xca, /* RETF 2 */
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2,
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0,
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};
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u_char hardint_trampoline[] = {
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0xf4, /* HLT */
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0xcf, /* IRET */
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};
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u_char null_trampoline[] = {
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0xcf, /* IRET */
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};
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u_long
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insert_generic_trampoline(size_t len, u_char *p)
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{
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u_char *q;
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u_long where;
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where = trampoline_rover;
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q = (u_char *)VECPTR(where);
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memcpy(q, p, len);
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trampoline_rover += len;
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return (where);
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}
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u_long
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insert_softint_trampoline(void)
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{
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return (insert_generic_trampoline(
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sizeof(softint_trampoline), softint_trampoline));
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}
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u_long
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insert_hardint_trampoline(void)
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{
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return (insert_generic_trampoline(
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sizeof(hardint_trampoline), hardint_trampoline));
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}
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u_long
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insert_null_trampoline(void)
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{
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return (insert_generic_trampoline(
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sizeof(null_trampoline), null_trampoline));
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}
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