Topic       : TOS - The Operating System
Author      : 
Version     : tos.hyp (December 19, 2008)
Subject     : Programmieren/Atari
Nodes       : 3010
Index Size  : 93790
HCP-Version : 5
Compiled on : Atari
@charset    : atarist
@lang       : 
@default    : Title
@help       : 
@options    : +g -i -s +x +zz -t4
@width      : 70
View Ref-File7.13.2  COLOR_RGB                                                  TOS

typedef struct
{
   uint16   reserved;     /* Set to 0 or the index of the entry */
   uint16   red;          /* Red:   0<->65535 */
   uint16   green;        /* Green: 0<->65535 */
   uint16   blue;         /* Blue:  0<->65535 */
} COLOR_RGB;

If the colour data in a program is present in a sensible format (e.g. 
8 bits per channel) already, one can save oneself a transformation 
with multiplication and division. The Shift and OR functions of the 
processor perform this faster and more elegantly. eleganter.

Example: The colour value is described by the byte variables r, g, b. 
The correct conversion to the 16-bit format of the COLOR_RGB structure 
proceeds as follows:

COLOR_RGB color;

color.reserved = 0;

color.red = r;
color.red |= (color.red << 8);

color.green = g;
color.green |= (color.green << 8);

color.blue = b;
color.blue |= (color.blue << 8);

The structure element reserved should be set to 0 or (for building up 
a colour table) contain the index of the entry. In each case, however, 
the upper 8 bits of reserved must be set to 0, as they may be used by 
the colour routines for some flags.