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 #include <syslinux/video.h>
  13
  14 __export void writechr(char data)
  15 {
  16         if (UsingVGA & 0x08)
  17                 syslinux_force_text_mode();
  18
  19         write_serial(data);     /* write to serial port if needed */
  20
  21         /* Write to screen? */
  22         if (DisplayCon & 0x01) {
  23                 com32sys_t ireg, oreg;
  24                 bool curxyok = false;
  25                 uint16_t dx;
  26
  27                 ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  28                 ireg.eax.b[1] = 0x03; /* Read cursor position */
  29                 __intcall(0x10, &ireg, &oreg);
  30                 ireg.edx.l = oreg.edx.l;
  31
  32                 switch (data) {
  33                 case 8:
  34                         if (ireg.edx.b[0]--) {
  35                                 curxyok = true;
  36                                 break;
  37                         }
  38
  39                         ireg.edx.b[0] = VidCols;
  40                         if (ireg.edx.b[1]--) {
  41                                 curxyok = true;
  42                                 break;
  43                         }
  44
  45                         ireg.edx.b[1] = 0;
  46                         curxyok = true;
  47                         break;
  48                 case 13:
  49                         ireg.edx.b[0] = 0;
  50                         curxyok = true;
  51                         break;
  52                 case 10:
  53                         break;
  54                 default:
  55                         dx = ireg.edx.w[0];
  56
  57                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  58                         ireg.ebx.b[0] = 0x07; /* White on black */
  59                         ireg.ecx.w[0] = 1;    /* One only */
  60                         ireg.eax.b[0] = data;
  61                         ireg.eax.b[1] = 0x09; /* Write char and attribute */
  62                         __intcall(0x10, &ireg, NULL);
  63
  64                         ireg.edx.w[0] = dx;
  65                         if (++ireg.edx.b[0] <= VidCols)
  66                                 curxyok = true;
  67                         else
  68                                 ireg.edx.b[0] = 0;
  69                 }
  70
  71                 if (!curxyok && ++ireg.edx.b[1] > VidRows) {
  72                         /* Scroll */
  73                         ireg.edx.b[1]--;
  74                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  75                         ireg.eax.b[1] = 0x02;
  76                         __intcall(0x10, &ireg, NULL);
  77
  78                         ireg.eax.w[0] = 0x0601; /* Scroll up one line */
  79                         ireg.ebx.b[1] = ScrollAttribute;
  80                         ireg.ecx.w[0] = 0;
  81                         ireg.edx.w[0] = ScreenSize; /* The whole screen */
  82                         __intcall(0x10, &ireg, NULL);
  83                 } else {
  84                         ireg.ebx.b[1] = *(uint8_t *)BIOS_page;
  85                         ireg.eax.b[1] = 0x02; /* Set cursor position */
  86                         __intcall(0x10, &ireg, NULL);
  87                 }
  88         }
  89 }
  90
  91 void pm_writechr(com32sys_t *regs)
  92 {
  93         writechr(regs->eax.b[0]);
  94 }