Re: [x86 setup 17/33] A20 handling code
From: Jan Engelhardt
Date: Tue Jul 10 2007 - 14:28:04 EST
On Jul 9 2007 19:51, H. Peter Anvin wrote:
>+ status = inb(0x64);
>+ if (status & 1) {
>+ /* Read and discard input data */
>+ io_delay();
>+ (void)inb(0x60);
Is the (void) cast needed for some obscure reason? Let's hope inb _is_ declared
as volatile. (Minus the volatile flames.
>+ } else if (!(status & 2)) {
>+ /* Buffers empty, finished! */
>+ return 0;
>+ }
>+ }
>+
>+ return -1;
>+}
>+
>+
>+#define A20_TEST_ADDR (4*0x80)
>+#define A20_TEST_SHORT 32
>+#define A20_TEST_LONG 2097152 /* 2^21 */
Maybe...?
#define A20_TEST_LONG (1 << 21)
>+/* Quick test to see if A20 is already enabled */
>+static int a20_test_short(void)
>+{
>+ return a20_test(A20_TEST_SHORT);
>+}
>+
>+/* Longer test that actually waits for A20 to come on line; this
>+ is useful when dealing with the KBC or other slow external circuitry. */
>+static int a20_test_long(void)
>+{
>+ return a20_test(A20_TEST_LONG);
>+}
To me looks like some of these (or other functions) could return bool.
Jan
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