Bob manipulation routines

/* Blitting operations: blit Bob, store and restore background. */

#include <hardware/blit.h>
#include <hardware/custom.h>
#include <graphics/gfx.h>
#include <clib/graphics_protos.h>

#include "Blit.h"

extern __far struct Custom custom;

/* Prepare Bob mask. Mask must be cleared. */
void prepBobMask(struct BitMap *bob, UBYTE *mask)
{
    /* Prepare variables */
    /* D = A + B */
    UWORD bltcon0    = SRCA | SRCB | DEST | ABC | ABNC | ANBC | ANBNC | NABC | NABNC;
    UWORD bltcon1    = 0;
    UWORD bpr        = bob->BytesPerRow;
    UWORD bltawm     = 0xffff;
    UWORD bltsizv    = bob->Rows;
    UWORD bltsizh    = bpr >> 1;
    UWORD depth      = bob->Depth;
    UBYTE *bobplane;

    UWORD i;

    OwnBlitter();

    for (i = 0; i < depth; i++)
        {
        bobplane = bob->Planes[i];
        WaitBlit();
        custom.bltcon0 = bltcon0;
        custom.bltcon1 = bltcon1;
        custom.bltapt  = bobplane;
        custom.bltbpt  = mask;
        custom.bltdpt  = mask;
        custom.bltamod = 0;
        custom.bltbmod = 0;
        custom.bltdmod = 0;
        custom.bltafwm = bltawm;
        custom.bltalwm = bltawm;
        custom.bltsize = (bltsizv << HSIZEBITS) | bltsizh;
        }
    DisownBlitter();
}

/* Blit Bob into background */
void blitBob(struct BitMap *bob, UBYTE *mask, struct BitMap *back, WORD x, WORD y)
{
    /* Prepare variables */
    UWORD shift      = x & 15; /* Shift value */
    /* D = AB + aC */
    UWORD bltcon0    = SRCA | SRCB | SRCC | DEST | ABC | ABNC | NABC | NANBC | (shift << ASHIFTSHIFT);
    UWORD bltcon1    = (shift << BSHIFTSHIFT);
    UWORD bobbpr     = bob->BytesPerRow;
    UWORD backbpr    = back->BytesPerRow;
    UWORD backoffset = (y * backbpr) + ((x >> 4) << 1); /* Offset to destination place in bitplane */
    WORD  bobmodulo  = -2;
    WORD  backmodulo = backbpr - bobbpr - 2;
    UWORD bltafwm    = 0xffff;
    UWORD bltalwm    = 0x0000;
    UWORD bltsizv    = bob->Rows;
    UWORD bltsizh    = (bobbpr >> 1) + 1;
    UWORD depth      = bob->Depth;
    UBYTE *bobplane,
          *backplane;

    UWORD i;

    OwnBlitter();

    for (i = 0; i < depth; i++)
        {
        bobplane  = bob->Planes[i];
        backplane = back->Planes[i] + backoffset;
        WaitBlit();
        custom.bltcon0 = bltcon0;
        custom.bltcon1 = bltcon1;
        custom.bltapt  = mask;
        custom.bltbpt  = bobplane;
        custom.bltcpt  = backplane;
        custom.bltdpt  = backplane;
        custom.bltamod = bobmodulo;
        custom.bltbmod = bobmodulo;
        custom.bltcmod = backmodulo;
        custom.bltdmod = backmodulo;
        custom.bltafwm = bltafwm;
        custom.bltalwm = bltalwm;
        custom.bltsize = (bltsizv << HSIZEBITS) | bltsizh;
        }
    DisownBlitter();
}

/* Store/Re-store Bob background */
void storeBack(struct BitMap *back, WORD x, WORD y, struct BitMap *store, UBYTE op)
{
    /* Prepare variables */
    /* D = A */
    UWORD bltcon0    = SRCA | DEST | ABC | ABNC | ANBC | ANBNC;
    UWORD bltcon1    = 0;
    UWORD backbpr    = back->BytesPerRow;
    UWORD backoffset = (y * backbpr) + ((x >> 4) << 1);
    UWORD storeoff   = 0;
    UWORD storebpr   = store->BytesPerRow;
    WORD  backmodulo = backbpr - storebpr;
    WORD  storemod   = 0;
    UWORD bltawm     = 0xffff;
    UWORD bltsizv    = store->Rows;
    UWORD bltsizh    = storebpr >> 1;
    UWORD depth      = store->Depth;
    UBYTE *backplane,
          *storeplane;

    UWORD i;

    if (op == RESTORE)
        {
        /* Re-storing: swap pointers and modulos */
        struct BitMap *auxbm;
        WORD          auxmod;
        UWORD         auxoff;

        auxbm = back;
        back  = store;
        store = auxbm;

        auxmod     = backmodulo;
        backmodulo = storemod;
        storemod   = auxmod;

        auxoff     = backoffset;
        backoffset = storeoff;
        storeoff   = auxoff;
        }

    OwnBlitter();

    for (i = 0; i < depth; i++)
        {
        backplane = back->Planes[i] + backoffset;
        storeplane = store->Planes[i] + storeoff;
        WaitBlit();
        custom.bltcon0 = bltcon0;
        custom.bltcon1 = bltcon1;
        custom.bltapt  = backplane;
        custom.bltdpt  = storeplane;
        custom.bltamod = backmodulo;
        custom.bltdmod = storemod;
        custom.bltafwm = bltawm;
        custom.bltalwm = bltawm;
        custom.bltsize = (bltsizv << HSIZEBITS) | bltsizh;
        }
    DisownBlitter();
}