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8bitworkshop/presets/coleco/mode2bitmap.c
2019-12-02 22:16:11 -06:00

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/*
Displays a bitmap using the TMS9928A's Mode 2.
In Mode 2, the screen is horizontally divided into three
256×64 pixel areas, each of which gets its own character
set. By sequentially printing the characters 0 through 255
in all three areas, the program can simulate a graphics mode
where each pixel can be set individually.
The limitation is that every horizontal run of 8 pixels
can only have two colors (a foreground and background color.)
The included Mode 2 bitmap was converted with a web utility:
http://msx.jannone.org/conv/
*/
#include <stdlib.h>
#include <cv.h>
#include <cvu.h>
#include "common.h"
/* link in MODE 2 bitmap data */
//#link "sailboat.s"
extern const unsigned char msx_bitmap[0x3807];
void setup_mode2() {
cvu_vmemset(0, 0, 0x4000);
cv_set_screen_mode(CV_SCREENMODE_BITMAP); // mode 2
cv_set_image_table(IMAGE);
cv_set_character_pattern_t(PATTERN|0x1fff); // AND mask
cv_set_color_table(COLOR|0x1fff); // AND mask
cv_set_sprite_attribute_table(SPRITES);
}
void main() {
// turn off screen
cv_set_screen_active(false);
// setup mode 2 grpahics
setup_mode2();
// copy pattern and color tables
cvu_memtovmemcpy(PATTERN, msx_bitmap+7, 0x1800);
cvu_memtovmemcpy(COLOR, msx_bitmap+7+COLOR, 0x1800);
// set IMAGE table to incrementing values
for (int i=0; i<0x300; i++) {
cvu_voutb(i, IMAGE+i);
}
// clear sprite table
cvu_vmemset(SPRITES, 0, 0x100);
// turn off screen
cv_set_screen_active(true);
while (1) {
//cv_set_character_pattern_t(PATTERN|rand()); // AND mask
//cv_set_color_table(COLOR|rand()); // AND mask
}
}