source: buchla-68k/vlib/vsetpal.c@ 4b63bf3

/*
   =============================================================================
        vsetpal.c -- Buchla 700 color palette setup
        Version 2 -- 1987-11-20 -- D.N. Lynx Crowe
   =============================================================================
*/

#include "ram.h"

#define PALETTE         ((volatile uint16_t *)0x280000L)

int16_t dfltpal[16][3] = {

/*       R  G  B          color */

        {0, 0, 0},      /*  0: Black */
        {0, 1, 0},      /*  1: Dark Gray */
        {0, 0, 2},      /*  2: Dark Blue */
        {0, 0, 3},      /*  3: Light Blue */
        {0, 2, 0},      /*  4: Dark Green */
        {0, 3, 0},      /*  5: Light Green */
        {0, 2, 2},      /*  6: Dark Cyan */
        {0, 3, 3},      /*  7: Light Cyan */
        {3, 0, 0},      /*  8: Red */
        {3, 1, 0},      /*  9: Orange */
        {3, 0, 3},      /* 10: Purple */
        {3, 1, 2},      /* 11: Magenta */
        {3, 2, 0},      /* 12: Brown */
        {2, 3, 0},      /* 13: Yellow */
        {2, 2, 2},      /* 14: Light Gray */
        {3, 3, 3},      /* 15: White */
};

/*
   =============================================================================
        vsetpal() -- set a palette RAM entry to a specific color

        slot    0..15   color entry number
        red     0..3    red value
        grn     0..3    green value
        blu     0..3    blue value
   =============================================================================
*/

void vsetpal(int16_t slot, int16_t red, int16_t grn, int16_t blu)
{
        int16_t palval;
        volatile uint16_t *pal;

        pal = PALETTE;

        palval = (slot << 6) |
                 ((red & 1) << 5) | ((red & 2) << 1) |
                 ((grn & 1) << 4) | (grn & 2) |
                 ((blu & 1) << 3) | ((blu & 2) >> 1);

        *pal = (uint16_t)palval ^ 0x003F;
}

/*
   =============================================================================
        vsndpal() -- send a palette table to the video palette RAM

        pp      pointer to a short [16][3] array,

                where:
                        pp[n][0]        = blue value
                        pp[n][1]        = green value
                        pp[n][2]        = red value

                                n       = slot number (0..15)
   =============================================================================
*/

void vsndpal(int16_t pp[16][3])
{
        register int16_t i;

        for (i = 0; i < 16; i++)
                vsetpal(i, pp[i][0], pp[i][1], pp[i][2]);
}