terminal.c

   1 /* terminal.c
   2  *
   3  * module for graphical output on the terminal
   4  *********************************************/
   5
   6 #include <stddef.h>
   7 #include <stdint.h>
   8 #include "terminal.h"
   9 #include "utils.h"
  10
  11 typedef struct {
  12     size_t   MAX_HEIGHT;
  13     size_t   MAX_WIDTH;
  14     size_t   row;
  15     size_t   column;
  16     VGAColor color;
  17     uint16_t *buffer;
  18 } Terminal;
  19
  20 Terminal term;
  21
  22 static uint8_t mkcolor(uint8_t fg, uint8_t bg);
  23 static uint16_t mkVGAentry(char c, uint8_t color);
  24 static void putCharAt(char c, uint8_t color, size_t i, size_t j);
  25 static void mvcursor();
  26 static void newline();
  27 static void scroll1();
  28
  29 /* clear the terminal */
  30 void term_clear(void)
  31 {
  32     term.row    = 0;
  33     term.column = 0;
  34
  35     for(size_t i = 0; i < term.MAX_HEIGHT; i++) {
  36         for(size_t j = 0; j < term.MAX_WIDTH; j++) {
  37             const size_t k = i * term.MAX_WIDTH + j;
  38             term.buffer[k] = mkVGAentry(' ', term.color);
  39         }
  40     }
  41 }
  42
  43
  44 /* initialize terminal to default values and draw all entries */
  45 void term_init(size_t max_width, size_t max_height, uint8_t fg, uint8_t bg)
  46 {
  47     term.MAX_HEIGHT = max_height;
  48     term.MAX_WIDTH  = max_width;
  49     term.row    = 0;
  50     term.column = 0;
  51     term.color  = mkcolor(fg,bg);
  52     term.buffer = (uint16_t*) 0xB8000;
  53
  54     for(size_t i = 0; i < max_height; i++) {
  55         for(size_t j = 0; j < max_width; j++) {
  56             const size_t k = i * max_width + j;
  57             term.buffer[k] = mkVGAentry(' ', term.color);
  58         }
  59     }
  60 }
  61
  62 /* draw char using current term settings, and update cursor position */
  63 void term_putChar(char c)
  64 {
  65     if(c == '\n') {
  66         newline();
  67     } else {
  68         putCharAt(c,term.color,term.column, term.row);
  69         mvcursor();
  70     }
  71 }
  72
  73
  74 void term_putStr(const char *str)
  75 {
  76     size_t len = strlen(str);
  77     for(size_t i = 0; i < len; i++)
  78         term_putChar(str[i]);
  79 }
  80
  81 void term_setcolor(uint8_t fg, uint8_t bg)
  82 {
  83     term.color = mkcolor(fg,bg);
  84 }
  85
  86 /*** static functions ***/
  87
  88 /* return color suitable for drawing on terminal */
  89 uint8_t mkcolor(uint8_t fg, uint8_t bg)
  90 {
  91     return fg | bg << 4;
  92 }
  93
  94 /* create an entry for drawing */
  95 uint16_t mkVGAentry(char c, uint8_t color)
  96 {
  97     uint16_t c16 = c;
  98     uint16_t color16 = color;
  99     return c16 | color16 << 8;
 100 }
 101
 102 /* draw entry at specified position */
 103 void putCharAt(char c, uint8_t color, size_t i, size_t j)
 104 {
 105     const size_t k = j * term.MAX_WIDTH + i;
 106     term.buffer[k] = mkVGAentry(c,color);
 107 }
 108
 109 void mvcursor()
 110 {
 111     if(++term.column == term.MAX_WIDTH)
 112         newline();
 113 }
 114
 115 void newline() {
 116     term.column = 0;
 117     if(term.row + 1 == term.MAX_HEIGHT)
 118         scroll1();
 119     else
 120         ++term.row;
 121 }
 122
 123 void scroll1()
 124 {
 125     for(size_t i = 0; i < term.MAX_HEIGHT - 1; i++) {
 126         for(size_t j = 0; j < term.MAX_WIDTH; j++) {
 127             const size_t k1 = i     * term.MAX_WIDTH + j;
 128             const size_t k2 = (i+1) * term.MAX_WIDTH + j;
 129             term.buffer[k1] = term.buffer[k2];
 130         }
 131     }
 132
 133     for(size_t j = 0; j < term.MAX_WIDTH; j++) {
 134         const size_t k = (term.MAX_HEIGHT - 1) * term.MAX_WIDTH + j;
 135         term.buffer[k] = mkVGAentry(' ', term.color);
 136     }
 137 }