core/rawcon.c

   1 /*
   2  * writechr:    Write a single character in AL to the console without
   3  *              mangling any registers.  This does raw console writes,
   4  *              since some PXE BIOSes seem to interfere regular console I/O.
   5  */
   6 #include <sys/io.h>
   7 #include <fs.h>
   8 #include <com32.h>
   9
  10 #include "bios.h"
  11 #include "graphics.h"
  12
  13 __export void writechr(char data)
  14 {
  15         if (UsingVGA & 0x08)
  16                 syslinux_force_text_mode();
  17
  18         write_serial(data);     /* write to serial port if needed */
  19
  20         /* Write to screen? */
  21         if (DisplayCon & 0x01) {
  22                 com32sys_t ireg, oreg;
  23                 bool curxyok = false;
  24                 uint16_t dx;
  25
  26                 ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  27                 ireg.eax.b[1] = 0x03; /* Read cursor position */
  28                 __intcall(0x10, &ireg, &oreg);
  29                 ireg.edx.l = oreg.edx.l;
  30
  31                 switch (data) {
  32                 case 8:
  33                         if (ireg.edx.b[0]--) {
  34                                 curxyok = true;
  35                                 break;
  36                         }
  37
  38                         ireg.edx.b[0] = VidCols;
  39                         if (ireg.edx.b[1]--) {
  40                                 curxyok = true;
  41                                 break;
  42                         }
  43
  44                         ireg.edx.b[1] = 0;
  45                         curxyok = true;
  46                         break;
  47                 case 13:
  48                         ireg.edx.b[0] = 0;
  49                         curxyok = true;
  50                         break;
  51                 case 10:
  52                         break;
  53                 default:
  54                         dx = ireg.edx.w[0];
  55
  56                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  57                         ireg.ebx.b[0] = 0x07; /* White on black */
  58                         ireg.ecx.w[0] = 1;    /* One only */
  59                         ireg.eax.b[0] = data;
  60                         ireg.eax.b[1] = 0x09; /* Write char and attribute */
  61                         __intcall(0x10, &ireg, NULL);
  62
  63                         ireg.edx.w[0] = dx;
  64                         if (++ireg.edx.b[0] <= VidCols)
  65                                 curxyok = true;
  66                         else
  67                                 ireg.edx.b[0] = 0;
  68                 }
  69
  70                 if (!curxyok && ++ireg.edx.b[1] > VidRows) {
  71                         /* Scroll */
  72                         ireg.edx.b[1]--;
  73                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  74                         ireg.eax.b[1] = 0x02;
  75                         __intcall(0x10, &ireg, NULL);
  76
  77                         ireg.eax.w[0] = 0x0601; /* Scroll up one line */
  78                         ireg.ebx.b[1] = ScrollAttribute;
  79                         ireg.ecx.w[0] = 0;
  80                         ireg.edx.w[0] = ScreenSize; /* The whole screen */
  81                         __intcall(0x10, &ireg, NULL);
  82                 } else {
  83                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  84                         ireg.eax.b[1] = 0x02; /* Set cursor position */
  85                         __intcall(0x10, &ireg, NULL);
  86                 }
  87         }
  88 }
  89
  90 void pm_writechr(com32sys_t *regs)
  91 {
  92         writechr(regs->eax.b[0]);
  93 }