// license:BSD-3-Clause // copyright-holders:Ville Laitinen, Aaron Giles /*************************************************************************** Sun Electronics Kangaroo hardware ***************************************************************************/ #include "emu.h" #include "includes/kangaroo.h" /************************************* * * Video setup * *************************************/ void kangaroo_state::video_start() { /* video RAM is accessed 32 bits at a time (two planes, 4bpp each, 4 pixels) */ m_videoram = std::make_unique(256 * 64); save_pointer(NAME(m_videoram), 256 * 64); } /************************************* * * Video RAM accesses * *************************************/ void kangaroo_state::videoram_write( uint16_t offset, uint8_t data, uint8_t mask ) { uint32_t expdata, layermask; /* data contains 4 2-bit values packed as DCBADCBA; expand these into 4 8-bit values */ expdata = 0; if (data & 0x01) expdata |= 0x00000055; if (data & 0x10) expdata |= 0x000000aa; if (data & 0x02) expdata |= 0x00005500; if (data & 0x20) expdata |= 0x0000aa00; if (data & 0x04) expdata |= 0x00550000; if (data & 0x40) expdata |= 0x00aa0000; if (data & 0x08) expdata |= 0x55000000; if (data & 0x80) expdata |= 0xaa000000; /* determine which layers are enabled */ layermask = 0; if (mask & 0x08) layermask |= 0x30303030; if (mask & 0x04) layermask |= 0xc0c0c0c0; if (mask & 0x02) layermask |= 0x03030303; if (mask & 0x01) layermask |= 0x0c0c0c0c; /* update layers */ m_videoram[offset] = (m_videoram[offset] & ~layermask) | (expdata & layermask); } WRITE8_MEMBER(kangaroo_state::kangaroo_videoram_w) { videoram_write(offset, data, m_video_control[8]); } /************************************* * * Video control writes * *************************************/ WRITE8_MEMBER(kangaroo_state::kangaroo_video_control_w) { m_video_control[offset] = data; switch (offset) { case 5: /* blitter start */ blitter_execute(); break; case 8: /* bank select */ membank("bank1")->set_entry((data & 0x05) ? 0 : 1); break; } } /************************************* * * DMA blitter * *************************************/ void kangaroo_state::blitter_execute( ) { uint32_t gfxhalfsize = memregion("gfx1")->bytes() / 2; const uint8_t *gfxbase = memregion("gfx1")->base(); uint16_t src = m_video_control[0] + 256 * m_video_control[1]; uint16_t dst = m_video_control[2] + 256 * m_video_control[3]; uint8_t height = m_video_control[5]; uint8_t width = m_video_control[4]; uint8_t mask = m_video_control[8]; int x, y; /* during DMA operations, the top 2 bits are ORed together, as well as the bottom 2 bits */ /* adjust the mask to account for this */ if (mask & 0x0c) mask |= 0x0c; if (mask & 0x03) mask |= 0x03; /* loop over height, then width */ for (y = 0; y <= height; y++, dst += 256) for (x = 0; x <= width; x++) { uint16_t effdst = (dst + x) & 0x3fff; uint16_t effsrc = src++ & (gfxhalfsize - 1); videoram_write(effdst, gfxbase[0 * gfxhalfsize + effsrc], mask & 0x05); videoram_write(effdst, gfxbase[1 * gfxhalfsize + effsrc], mask & 0x0a); } } /************************************* * * Video updater * *************************************/ uint32_t kangaroo_state::screen_update_kangaroo(screen_device &screen, bitmap_rgb32 &bitmap, const rectangle &cliprect) { uint8_t scrolly = m_video_control[6]; uint8_t scrollx = m_video_control[7]; uint8_t maska = (m_video_control[10] & 0x28) >> 3; uint8_t maskb = (m_video_control[10] & 0x07) >> 0; uint8_t xora = (m_video_control[9] & 0x20) ? 0xff : 0x00; uint8_t xorb = (m_video_control[9] & 0x10) ? 0xff : 0x00; uint8_t enaa = (m_video_control[9] & 0x08); uint8_t enab = (m_video_control[9] & 0x04); uint8_t pria = (~m_video_control[9] & 0x02); uint8_t prib = (~m_video_control[9] & 0x01); int x, y; /* iterate over pixels */ for (y = cliprect.min_y; y <= cliprect.max_y; y++) { uint32_t *dest = &bitmap.pix32(y); for (x = cliprect.min_x; x <= cliprect.max_x; x += 2) { uint8_t effxa = scrollx + ((x / 2) ^ xora); uint8_t effya = scrolly + (y ^ xora); uint8_t effxb = (x / 2) ^ xorb; uint8_t effyb = y ^ xorb; uint8_t pixa = (m_videoram[effya + 256 * (effxa / 4)] >> (8 * (effxa % 4) + 0)) & 0x0f; uint8_t pixb = (m_videoram[effyb + 256 * (effxb / 4)] >> (8 * (effxb % 4) + 4)) & 0x0f; uint8_t finalpens; /* for each layer, contribute bits if (a) enabled, and (b) either has priority or the opposite plane is 0 */ finalpens = 0; if (enaa && (pria || pixb == 0)) finalpens |= pixa; if (enab && (prib || pixa == 0)) finalpens |= pixb; /* store the first of two pixels, which is always full brightness */ dest[x + 0] = m_palette->pen_color(finalpens & 7); /* KOS1 alternates at 5MHz, offset from the pixel clock by 1/2 clock */ /* when 0, it enables the color mask for pixels with Z = 0 */ finalpens = 0; if (enaa && (pria || pixb == 0)) { if (!(pixa & 0x08)) pixa &= maska; finalpens |= pixa; } if (enab && (prib || pixa == 0)) { if (!(pixb & 0x08)) pixb &= maskb; finalpens |= pixb; } /* store the second of two pixels, which is affected by KOS1 and the A/B masks */ dest[x + 1] = m_palette->pen_color(finalpens & 7); } } return 0; }