send console output to parallel port

bf49aedb · rtm · 8352b998 · bf49aedb · bf49aedb
--- a/Notes
+++ b/Notes
+bochs 2.2.6:
+./configure --enable-smp --enable-disasm --enable-debugger --enable-all-optimizations --enable-4meg-pages --enable-global-pages --enable-pae --disable-reset-on-triple-fault
 bootmain.c doesn't work right if the ELF sections aren't
 sector-aligned. so you can't use ld -N. and the sections may also need
 to be non-zero length, only really matters for tiny "kernels".

--- a/console.c
+++ b/console.c
@@ -2,6 +2,23 @@
 #include <x86.h>
 #include "defs.h"
+/*
+ * copy console output to parallel port, which you can tell
+ * .bochsrc to copy to the stdout:
+ * parport1: enabled=1, file="/dev/stdout"
+ */
+static void
+lpt_putc(int c)
+{
+	int i;
+	for (i = 0; !(inb(0x378+1) & 0x80) && i < 12800; i++)
+		;
+	outb(0x378+0, c);
+	outb(0x378+2, 0x08|0x04|0x01);
+	outb(0x378+2, 0x08);
+}
 void
 cons_putc(int c)
 {
@@ -9,6 +26,8 @@ cons_putc(int c)
  unsigned short *crt = (unsigned short *) 0xB8000; // base of CGA memory
  int ind;
+  lpt_putc(c);
  // cursor position, 16 bits, col + 80*row
  outb(crtport, 14);
  ind = inb(crtport + 1) << 8;