/* ************************************************************************** */
/*                                       _____           _                    */
/*  ML_bmp.c                            |_   _|__  _   _| |__   ___ _   _     */
/*  | Project : libmonochrome             | |/ _ \| | | | '_ \ / _ \ | | |    */
/*                                        | | (_) | |_| | | | |  __/ |_| |    */
/*  By: thomas <thomas@touhey.fr>         |_|\___/ \__,_|_| |_|\___|\__, |.fr */
/*  Last updated: 2016/05/29 01:55:54                               |___/     */
/*                                                                            */
/* ************************************************************************** */

#include <monochrome/internals.h>

static inline void ML_bmp_line(unsigned char *vram, const unsigned char *b,
	int width, int offset, ML_Mode mode);
static inline void ML_bmp_byte(unsigned char *v, int b, int offset, int width,
	ML_Mode mode);

void ML_bmp(const void *bmp, int x, int y, int width, int height, ML_Mode mode)
{
	/* FIXME: no support for non-clipping blit. */
	/* Oh, and yeah : most of this code is adapted from Caphics.
	   Clipping is, of course, on by default, and this function is not
	   optimized for when its disabled. */

	if (x < width + 1 || x >= 128 || y < height + 1 || y >= 64)
		return ;
	// check clipping for retrocompatibility ?

	int ls = (width >> 3) + ((width & 7) != 0); // line size
	const unsigned char *b = (const unsigned char*)bmp;

	// pass first lines
	if (y < 0) {
		b += -y * ls;
		height += y;
		y = 0;
	}
	if (height > 64 - y)
		height = 64 - y;

	// pass first pixels if x < 0
	int offset = 0;
	if (x < 0) {
		b += -x >> 3;
		width += x & 8;
		x = 0;
	}
	if (width > 128 - x)
		width = 128 - x;

	// go to first interesting byte of vram
	char *vram = ML_vram_xy(x, y);

	// then draw
	while (height--) {
		ML_bmp_line((unsigned char*)vram, b, width, offset, mode);
		vram += 8, bmp += ls;
	}
}

static inline void ML_bmp_line(unsigned char *vram, const unsigned char *b,
	int width, int offset, ML_Mode mode)
{
	while (1) {
		ML_bmp_byte(vram, *b, offset, width, mode);
		if (width < 8)
			break ;
		vram++, b++;
		width -= 8;
	}
}

static inline void ML_bmp_byte(unsigned char *v, int b, int offset, int width,
	ML_Mode mode)
{
	if (width < 8) b &= 255 << (8 - width);

	switch (mode) {
		case ML_MAND:
			*v &= ~(b >> offset);
			if (width > 8 - offset)
				*(++v) &= ~(b << (8 - offset));
			break;
		case ML_MOR:
			*v |= b >> offset;
			if (width > 8 - offset)
				*(++v) |= b << (8 - offset);
			break;
		case ML_MXOR:
			*v ^= b >> offset;
			if (width > 8 - offset)
				*(++v) ^= b << (8 - offset);
			break;
	}
}