Hi!
10-Мар-2006 07:49 [EMAIL PROTECTED] (Miguel) wrote to
[email protected]:
M> I am looking through the FreeDOS source, but someone might know the
M> answers ...
M> Q: Which interrupt vectors are hooked by FreeDOS?
main.c:
______________O\_/_________________________________\_/O______________
STATIC void setup_int_vectors(void)
{
static struct vec
{
unsigned char intno;
size_t handleroff;
} vectors[] =
{
/* all of these are in the DOS DS */
{ 0x0, FP_OFF(int0_handler) }, /* zero divide */
{ 0x1, FP_OFF(empty_handler) }, /* single step */
{ 0x3, FP_OFF(empty_handler) }, /* debug breakpoint */
{ 0x6, FP_OFF(int6_handler) }, /* invalid opcode */
{ 0x20, FP_OFF(int20_handler) },
{ 0x21, FP_OFF(int21_handler) },
{ 0x22, FP_OFF(int22_handler) },
{ 0x24, FP_OFF(int24_handler) },
{ 0x25, FP_OFF(low_int25_handler) },
{ 0x26, FP_OFF(low_int26_handler) },
{ 0x27, FP_OFF(int27_handler) },
{ 0x28, FP_OFF(int28_handler) },
{ 0x2a, FP_OFF(int2a_handler) },
{ 0x2f, FP_OFF(int2f_handler) }
};
struct vec *pvec;
int i;
for (i = 0x23; i <= 0x3f; i++)
setvec(i, empty_handler);
for (pvec = vectors; pvec < ENDOF(vectors); pvec++)
setvec(pvec->intno, (intvec)MK_FP(FP_SEG(empty_handler), pvec->handleroff));
pokeb(0, 0x30 * 4, 0xea);
pokel(0, 0x30 * 4 + 1, (ULONG)cpm_entry);
/* these two are in the device driver area LOWTEXT (0x70) */
setvec(0x1b, got_cbreak);
setvec(0x29, int29_handler); /* required for printf! */
}
_____________________________________________________________________
O/~\ /~\O
Here you may see, which FreeDOS hooks for own handlers and which initializes
to empty handler (which just IRETs).
M> For example, the timer ticker interrupt at 1Ch (or 08h).
For timer operation DOS uses BIOS.
M> Q: What is the highest numbered interrupt that is used by FreeDOS/MS-DOS ?
What mean "uses"? You mean, through which presents own services? INT2F.
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