/**
 * Chunky vertical copperbars demo
 * Copyright 2023 John Bintz
 * Licensed under the MIT License
 * https://theindustriousrabbit.com
 */
#include <clib/exec_protos.h>
#include <clib/dos_protos.h>
#include <clib/alib_protos.h>
#include <clib/intuition_protos.h>
#include <clib/graphics_protos.h>

#include <graphics/GfxBase.h>

#include <exec/memory.h>

#include <hardware/cia.h>
#include <hardware/dmabits.h>

#include <stdio.h>

extern struct GfxBase *GfxBase;
extern struct Custom far custom;
extern struct CIA far ciaa, ciab;

// this is faster than
// custom.vhposr + (custom.vposr << 16)
static volatile ULONG *custom_vposr = (volatile ULONG *)0xdff004;

#define offsetof(s, m) &((struct s *)0)->m
#define BITPLANE_SIZE (320/8)*256

#define BPLCON0_COLOR (0x200)
#define BPLCON0_BPU_1 (0x1000)

static UWORD colors[] = {0xf00,0x0f0,0xff0,0x0ff};

int main(void) {
  struct View *OldView = ((struct GfxBase *)GfxBase)->ActiView;
  ULONG OldCopper = (ULONG)((struct GfxBase *)GfxBase)->copinit;
  ULONG OldDMACON, OldINTENA, OldINTREQ, OldADKCON;

  int currentY, colorBar, xPos;

  void *copperlist;
  UWORD *copperlist_ptr;
  APTR *bitplane;

  // how much can we avoid hard coding into our code?
  UWORD custom_bplpt = (UWORD)offsetof(Custom, bplpt);
  UWORD custom_color = (UWORD)offsetof(Custom, color);

  LoadView(NULL);
  WaitTOF();
  WaitTOF();
  OwnBlitter();
  WaitBlit();
  Forbid();

  OldDMACON = custom.dmaconr | 0x8000;
  OldINTENA = custom.intenar | 0x8000;
  OldINTREQ = custom.intreqr | 0x8000;
  OldADKCON = custom.adkconr | 0x8000;

  // disable interrupts
  custom.intena = 0xc000;
  custom.intena = 0x3fff;

  // set up dma
  custom.dmacon = DMAF_SETCLR | DMAF_COPPER | DMAF_RASTER;
  custom.dmacon = DMAF_AUDIO | DMAF_DISK | DMAF_SPRITE | DMAF_BLITTER;

  // 4 bars = WAIT + MOVE (8 bytes) 8 times * 312 + ~100 for setup = 21000 should do it

  copperlist = AllocMem(21000, MEMF_CHIP | MEMF_CLEAR);
  bitplane   = (APTR *)AllocMem(BITPLANE_SIZE, MEMF_PUBLIC|MEMF_CHIP|MEMF_CLEAR);

  // default copperlist has just STOP
  ((ULONG *)copperlist)[0] = 0xfffffffe;

  // set up 1 bitplane pal display
  custom.bplcon0 = BPLCON0_COLOR | BPLCON0_BPU_1;
  custom.bplcon1 = 0;
  custom.bpl1mod = 0;
  custom.diwstrt = 0x2c21;
  custom.diwstop = 0x2cc1;
  custom.ddfstrt = 0x0038;
  custom.ddfstop = 0x00d0;

  // substitute our minimal copperlist now
  custom.cop1lc = (ULONG)copperlist;

  // neither HID button 0 is down
  while ((ciaa.ciapra >> 6) == 3) {
    // rebuild copperlist
    copperlist_ptr = (UWORD *)copperlist;

    // bpl1pth
    *(copperlist_ptr++) = custom_bplpt;
    *(copperlist_ptr++) = ((ULONG)bitplane >> 16) & 0xffff;
    // bpl1ptl
    *(copperlist_ptr++) = custom_bplpt + 2;
    *(copperlist_ptr++) = (ULONG)bitplane & 0xffff;

    *(copperlist_ptr++) = custom_color;
    *(copperlist_ptr++) = 0x0f00;

    for (currentY = 0; currentY < 312; currentY++) {
      for (colorBar = 0; colorBar < 4; colorBar++) {
        xPos = 0x68 + (colorBar * 24);

        *(copperlist_ptr++) = ((currentY & 0xff) << 8) | xPos | 0x1;
        *(copperlist_ptr++) = 0xfffe;

        *(copperlist_ptr++) = custom_color;
        *(copperlist_ptr++) = colors[colorBar];

        *(copperlist_ptr++) = ((currentY & 0xff) << 8) | xPos + 2 | 0x1;
        *(copperlist_ptr++) = 0xfffe;

        *(copperlist_ptr++) = custom_color;
        *(copperlist_ptr++) = 0x000;
      }

      // PAL workaround
      if (currentY == 255) {
        *(copperlist_ptr++) = 0xffdf;
        *(copperlist_ptr++) = 0xfffe;
      }
    }

    // end the copperlist
    *(copperlist_ptr++) = 0xffff;
    *(copperlist_ptr++) = 0xfffe;

    // vbl wait
    // this will not work on NTSC!
    while ((*custom_vposr & 0x1FF00) != (300 << 8)) {}
  }

  FreeMem(bitplane, BITPLANE_SIZE);
  FreeMem(copperlist, 21000);

  custom.dmacon = 0x7FFF;
  custom.dmacon = OldDMACON;
  custom.intena = 0x7FFF;
  custom.intena = OldINTENA;
  custom.intreq = 0x7FFF;
  custom.intreq = OldINTREQ;
  custom.adkcon = 0x7FFF;
  custom.adkcon = OldADKCON;

  custom.cop1lc = OldCopper;
  LoadView(OldView);
  WaitTOF();
  WaitTOF();
  WaitBlit();
  DisownBlitter();
  Permit();
}