/*
 *-----------------------------------------------------------------------------
 *
 * video.c --
 *
 *    Routines for printing to the VGA color text mode buffer.
 *
 *-----------------------------------------------------------------------------
 */

#include <cpuid.h>


/* VGA mem start address */
#define VGAMEM 0xb8000

#define NROWS 25
#define NCOLUMNS 80

#define COLOR 0x07

#define index(r,c) (2 * ((r) * NCOLUMNS + (c)))
#define at_end_of_line() (col == NCOLUMNS)
#define at_last_line() (row == NROWS - 1)


static char *vgamem = (char *)VGAMEM;

static unsigned long row = 0;
static unsigned long col = 0;



/*
 *-----------------------------------------------------------------------------
 *
 * scroll_up --
 *
 *    Scroll the VGA buffer up one line, blanking the line at the bottom.
 *
 *-----------------------------------------------------------------------------
 */

static void
scroll_up (void)
{
   memcpy ((void *)VGAMEM, (void *)(VGAMEM + NCOLUMNS * 2),
	   ((NROWS - 1) * NCOLUMNS * 2));

   /* zero the newly cleared last line */
   asm ("xorl  %%eax, %%eax\n"
        "\tmovl  %0, %%ecx\n"
        "\tmovl  %1, %%ebx\n"
        "1:\tmovl  %%eax, (%%ebx)\n"
        "\taddl  $4, %%ebx\n"
        "\tloop  1b\n"
        :: "i" (NCOLUMNS / 2),
        "i" (VGAMEM + (NROWS - 1) * NCOLUMNS * 2));

   col = 0;
}

void
goto_xy (unsigned long x, unsigned long y)
{
  col = (x > NCOLUMNS) ? NCOLUMNS : x;
  row = (y > NROWS) ? NROWS : y;
}

void
get_xy (unsigned long *x, unsigned long *y)
{
   *x = col;
   *y = row;
}


void
clear_screen (void)
{
  unsigned long *buf = (unsigned long *)vgamem;
  unsigned long cur;

  for (cur = 0; cur < 0x2000; cur++) {
    buf[cur] = 0;
  }

  col = 0;
  row = 0;
}


static void
newline (void)
{
   if (at_last_line ()) {
      scroll_up ();
   } else {
      row++;
   }

   col = 0;
}

static void
_putchar (char c)
{
   if (at_end_of_line ()) {
      newline ();
   } else if (c == '\n') {
      newline ();
      return;
   }

   *(vgamem + index (row, col)) = c;
   *(vgamem + index (row, col) + 1) = COLOR;

   col++;
}

void
print_str (char *msg)
{
   char c;
   int k = 0;

   while ((c = msg[k])) {
      _putchar (c);
      k++;
   }

   log_msg (msg);
}

void
putchar (char c)
{
   char buf[2];

   buf[0] = c;
   buf[1] = '\0';

   print_str (buf);
}

void
print_hex8 (unsigned char val)
{
   char str[3];
   char vals[] = "0123456789abcdef";
   int k;

   for (k = 0; k < 2; k++) {
      str[k] = vals[(val >> ((1-k) * 4)) & 0xf];
   }
   str[2] = '\0';

   print_str (str);
}

void
print_hex16 (unsigned short val)
{
   char str[5];
   char vals[] = "0123456789abcdef";
   int k;

   for (k = 0; k < 4; k++) {
      str[k] = vals[(val >> ((3-k) * 4)) & 0xf];
   }
   str[4] = '\0';

   print_str (str);
}

void
print_hex32 (unsigned long val)
{
   char str[9];
   char vals[] = "0123456789abcdef";
   int k;

   for (k = 0; k < 8; k++) {
      str[k] = vals[(val >> ((7-k) * 4)) & 0xf];
   }
   str[8] = '\0';

   print_str (str);
}

void
print_hex64 (unsigned long long val)
{
   char str[17];
   char vals[] = "0123456789abcdef";
   int k;

   for (k = 0; k < 16; k++) {
      str[k] = vals[(val >> ((15-k) * 4)) & 0xf];
   }
   str[16] = '\0';

   print_str (str);
}

void
dump_cpu (void)
{
   unsigned long eax, ebx, ecx, edx, esi, edi, ebp, esp;
   unsigned long cr0, cr2, cr3, cr4, eflags;

   asm ("movl %%eax, %[eax]\n\t"
        "movl %%ebx, %[ebx]\n\t"
        "movl %%ecx, %[ecx]\n\t"
        "movl %%edx, %[edx]\n\t"
        "movl %%esi, %[esi]\n\t"
        "movl %%edi, %[edi]\n\t"
        "movl %%ebp, %[ebp]\n\t"
        "movl %%esp, %[esp]\n\t"
        "movl %%cr0, %%eax\n\t"
        "movl %%eax, %[cr0]\n\t"
        "movl %%cr2, %%eax\n\t"
        "movl %%eax, %[cr2]\n\t"
        "movl %%cr3, %%eax\n\t"
        "movl %%eax, %[cr3]\n\t"
        "movl %%cr4, %%eax\n\t"
        "movl %%eax, %[cr4]\n\t"
        "pushf\n\t"
        "popl %%eax\n"
        "movl %%eax, %[eflags]\n\t"
        : [eax] "=m" (eax),
        [ebx] "=m" (ebx),
        [ecx] "=m" (ecx),
        [edx] "=m" (edx),
        [esi] "=m" (esi),
        [edi] "=m" (edi),
        [ebp] "=m" (ebp),
        [esp] "=m" (esp),
        [cr0] "=m" (cr0),
        [cr2] "=m" (cr2),
        [cr3] "=m" (cr3),
        [cr4] "=m" (cr4),
        [eflags] "=m" (eflags)
        :);

   printf ("EAX %08lx  EBX %08lx  ECX %08lx  EDX %08lx\n"
           "ESI %08lx  EDI %08lx  EBP %08lx  ESP %08lx\n"
           "CR0 %08lx  CR2 %08lx  CR3 %08lx  CR4 %08lx\n"
           "EFLAGS %08lx\n",
           eax, ebx, ecx, edx, esi, edi, ebp, esp, cr0, cr2, cr3, cr4, eflags);
}