freebsd-src/usr.bin/doscmd/dispatch.h
1999-08-28 01:08:13 +00:00

111 lines
3.5 KiB
C

/*
** Copyright (c) 1996
** Michael Smith. All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
** 1. Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
**
** THIS SOFTWARE IS PROVIDED BY Michael Smith ``AS IS'' AND
** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
** ARE DISCLAIMED. IN NO EVENT SHALL Michael Smith BE LIABLE
** FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
** DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
** OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
** OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
** SUCH DAMAGE.
**
** $FreeBSD$
*/
/*
** Interrupt dispatcher assistants.
*/
/*
** Declare a static, initialised array of these, with one
** entry per function/subfunction.
**
** The last element should be a dummy with a 'func' of -1
*/
struct intfunc_table
{
int func; /* interrupt function number */
int subfunc; /* subfunction number */
int (* handler)(regcontext_t *REGS);/* handling function */
const char *desc; /* textual description */
};
#define IFT_NOSUBFUNC -1
/*
** Declare a static array of 256 integers to use as a fast lookup
** into the table of handlers.
**
** Call this function to initialise the lookup. Note that the table
** must be arranged with all handlers for a given function together, and
** that the handler listed with IFT_NOSUBFUNC should be last.
*/
static inline void
intfunc_init(struct intfunc_table table[], int index[])
{
int hn;
for (hn = 0; hn < 256; hn++) /* initialise all no-handler state */
index[hn] = -1; /* default to no handler */
for (hn = 0; table[hn].func >= 0; hn++) /* walk list of handlers and add references */
if (index[table[hn].func] == -1 ) /* reference first handler */
index[table[hn].func] = hn;
}
/*
** Call this to get an index matching the function/subfunction
** described by (sc), or -1 if none exist
*/
static inline int
intfunc_find(struct intfunc_table table[], int index[], int func, int subfunc)
{
int ent = index[func]; /* look for handler */
while ((ent >= 0) && /* scan entries for function */
(table[ent].func == func)) {
if ((table[ent].subfunc == IFT_NOSUBFUNC) || /* handles all */
(table[ent].subfunc == subfunc)) { /* handles this one */
return(ent);
}
ent++;
}
return(-1);
}
/*
** A slower lookup for a set of function handlers, but one that requires
** no initialisation calls.
** Again, handlers with IFT_NOSUBFUNC should be listed after any with
** specific subfunction values.
*/
static inline int
intfunc_search(struct intfunc_table table[], int func, int subfunc)
{
int ent;
for (ent = 0; table[ent].func >= 0; ent++)
if ((table[ent].func == func) && /* matches required function */
((table[ent].subfunc == IFT_NOSUBFUNC) || table[ent].subfunc == subfunc))
return(ent);
return(-1);
}