interrupts, timer, keyboard, segments, lots of kernel code

[bootcensus] / src / keyb.c

diff --git a/src/keyb.c b/src/keyb.c
new file mode 100644 (file)
index 0000000..c5a672c
--- /dev/null
+++ b/src/keyb.c
@@ -0,0 +1,132 @@
+#include "keyb.h"
+#include "intr.h"
+#include "asmops.h"
+
+#define KB_IRQ 1
+#define KB_PORT                0x60
+
+/* table with rough translations from set 1 scancodes to ASCII-ish */
+static int scantbl[] = {
+       0, KB_ESC, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-', '=', '\b',            /* 0 - e */
+       '\t', 'q', 'w', 'e', 'r', 't', 'y', 'u', 'i', 'o', 'p', '[', ']', '\n',                 /* f - 1c */
+       KB_LCTRL, 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', ';', '\'', '`',                          /* 1d - 29 */
+       KB_LSHIFT, '\\', 'z', 'x', 'c', 'v', 'b', 'n', 'm', ',', '.', '/', KB_RSHIFT,                   /* 2a - 36 */
+       KB_NUM_MUL, KB_LALT, ' ', KB_CAPSLK, KB_F1, KB_F2, KB_F3, KB_F4, KB_F5, KB_F6, KB_F7, KB_F8, KB_F9, KB_F10,                     /* 37 - 44 */
+       KB_NUMLK, KB_SCRLK, KB_NUM_7, KB_NUM_8, KB_NUM_9, KB_NUM_MINUS, KB_NUM_4, KB_NUM_5, KB_NUM_6, KB_NUM_PLUS,      /* 45 - 4e */
+       KB_NUM_1, KB_NUM_2, KB_NUM_3, KB_NUM_0, KB_NUM_DOT, KB_SYSRQ, 0, 0, KB_F11, KB_F12,                                             /* 4d - 58 */
+       0, 0, 0, 0, 0, 0, 0,                                                                                                                    /* 59 - 5f */
+       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,                                                                 /* 60 - 6f */
+       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0                                                                  /* 70 - 7f */
+};
+
+static void kbintr();
+
+#define BUFSZ  64
+#define ADVANCE(x)     ((x) = ((x) + 1) & (BUFSZ - 1))
+
+static int buffer[BUFSZ];
+static int buf_ridx, buf_widx;
+
+static unsigned int num_pressed;
+static unsigned char keystate[256];
+
+void kb_init(void)
+{
+       interrupt(IRQ_TO_INTR(KB_IRQ), kbintr);
+}
+
+int kb_isdown(int key)
+{
+       switch(key) {
+       case KB_ANY:
+               return num_pressed;
+
+       case KB_ALT:
+               return keystate[KB_LALT] + keystate[KB_RALT];
+
+       case KB_CTRL:
+               return keystate[KB_LCTRL] + keystate[KB_RCTRL];
+       }
+       return keystate[key];
+}
+
+void kb_wait(void)
+{
+       int key;
+       while((key = kb_getkey()) == -1) {
+               /* put the processor to sleep while waiting for keypresses, but first
+                * make sure interrupts are enabled, or we'll sleep forever
+                */
+               enable_intr();
+               halt_cpu();
+       }
+       kb_putback(key);
+}
+
+int kb_getkey(void)
+{
+       int res;
+
+       if(buf_ridx == buf_widx) {
+               return -1;
+       }
+       res = buffer[buf_ridx];
+       ADVANCE(buf_ridx);
+       return res;
+}
+
+void kb_putback(int key)
+{
+       /* go back a place */
+       if(--buf_ridx < 0) {
+               buf_ridx += BUFSZ;
+       }
+
+       /* if the write end hasn't caught up with us, go back one place
+        * and put it there, otherwise just overwrite the oldest key which
+        * is right where we were.
+        */
+       if(buf_ridx == buf_widx) {
+               ADVANCE(buf_ridx);
+       }
+
+       buffer[buf_ridx] = key;
+}
+
+static void kbintr()
+{
+       unsigned char code;
+       int key, press;
+
+       code = inb(KB_PORT);
+
+       if(code >= 128) {
+               press = 0;
+               code -= 128;
+
+               if(num_pressed > 0) {
+                       num_pressed--;
+               }
+       } else {
+               press = 1;
+
+               num_pressed++;
+       }
+
+       key = scantbl[code];
+
+       if(press) {
+               /* append to buffer */
+               buffer[buf_widx] = key;
+               ADVANCE(buf_widx);
+               /* if the write end overtook the read end, advance the read end
+                * too, to discard the oldest keypress from the buffer
+                */
+               if(buf_widx == buf_ridx) {
+                       ADVANCE(buf_ridx);
+               }
+       }
+
+       /* and update keystate table */
+       keystate[key] = press;
+}