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/* ****************************************************************************
* horizontal_scroll.c -- Scroll the screen horizontally.
*
* Copyright (C) 2011 Pierre Le Gall <legallpierre89@gmail.com>
* Copyright (C) 2016-2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
*
* This file is part of the 'casiowin/monochromelib' module in libcarrot, an
* experimental modular libc project.
*
* This file is free software: you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option)
* any later version.
*
* This file is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Lesser Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this file. If not, see <http://www.gnu.org/licenses/>.
* ************************************************************************* */
#include <monochrome.h>
void ML_horizontal_scroll(int scroll)
{
int i, j;
char line[16], shift, *vram;
unsigned char next;
unsigned short word;
vram = ML_vram_adress();
scroll %= 128;
shift = 8-(scroll&7);
for(i=0 ; i<64 ; i++)
{
for(j=0 ; j<16 ; j++) line[j] = vram[(i<<4)+((j-(scroll>>3)+15)&15)];
next = line[15];
vram[(i<<4)+15] = 0;
for(j=15 ; j>0 ; j--)
{
word = next << shift;
next = line[j-1];
vram[(i<<4)+j] |= *((char*)&word+1);
vram[(i<<4)+j-1] = *((char*)&word);
}
word = next << shift;
vram[(i<<4)] |= *((char*)&word+1);
vram[(i<<4)+15] |= *((char*)&word);
}
}
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