xv6-cs450/kbd.c

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#include "types.h"
#include "x86.h"
#include "defs.h"
#include "kbd.h"
int
kbdgetc(void)
{
static uint shift;
static uchar *charcode[4] = {
normalmap, shiftmap, ctlmap, ctlmap
};
uint st, data, c;
st = inb(KBSTATP);
if((st & KBS_DIB) == 0)
return -1;
data = inb(KBDATAP);
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if(data == 0xE0){
shift |= E0ESC;
return 0;
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} else if(data & 0x80){
// Key released
data = (shift & E0ESC ? data : data & 0x7F);
shift &= ~(shiftcode[data] | E0ESC);
return 0;
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} else if(shift & E0ESC){
// Last character was an E0 escape; or with 0x80
data |= 0x80;
shift &= ~E0ESC;
}
shift |= shiftcode[data];
shift ^= togglecode[data];
c = charcode[shift & (CTL | SHIFT)][data];
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if(shift & CAPSLOCK){
if('a' <= c && c <= 'z')
c += 'A' - 'a';
else if('A' <= c && c <= 'Z')
c += 'a' - 'A';
}
return c;
}
void
kbdintr(void)
{
consoleintr(kbdgetc);
}