V9990PxConverter.cc

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#include "V9990PxConverter.hh"
#include "V9990.hh"
#include "V9990VRAM.hh"
#include "ScopedAssign.hh"
#include "narrow.hh"
#include "ranges.hh"
#include <array>
#include <cassert>
#include <algorithm>
#include <cstdint>
#include <optional>
 
namespace openmsx {
 
using Pixel = V9990P1Converter::Pixel;
 
V9990P1Converter::V9990P1Converter(V9990& vdp_, std::span<const Pixel, 64> palette64_)
        : vdp(vdp_), vram(vdp.getVRAM())
        , palette64(palette64_)
{
}
 
V9990P2Converter::V9990P2Converter(V9990& vdp_, std::span<const Pixel, 64> palette64_)
        : vdp(vdp_), vram(vdp.getVRAM()), palette64(palette64_)
{
}
 
struct P1Policy {
        static byte readNameTable(const V9990VRAM& vram, unsigned addr) {
                return vram.readVRAMP1(addr);
        }
        static byte readPatternTable(const V9990VRAM& vram, unsigned addr) {
                return vram.readVRAMP1(addr);
        }
        static byte readSpriteAttr(const V9990VRAM& vram, unsigned addr) {
                return vram.readVRAMP1(addr);
        }
        static unsigned spritePatOfst(byte spriteNo, byte spriteY) {
                return (128 * ((spriteNo & 0xF0) + spriteY))
                     + (  8 *  (spriteNo & 0x0F));
        }
        static constexpr unsigned SCREEN_WIDTH = 256;
        static constexpr unsigned IMAGE_WIDTH = 2 * SCREEN_WIDTH;
        static constexpr unsigned NAME_CHARS = IMAGE_WIDTH / 8;
        static constexpr unsigned PATTERN_CHARS = SCREEN_WIDTH / 8;
};
struct P1BackgroundPolicy : P1Policy {
        static void draw1(
                std::span<const Pixel, 16> palette, Pixel* __restrict buffer,
                byte* __restrict /*info*/, size_t p)
        {
                *buffer = palette[p];
        }
        static constexpr bool DRAW_BACKDROP = true;
};
struct P1ForegroundPolicy : P1Policy {
        static void draw1(
                std::span<const Pixel, 16> palette, Pixel* __restrict buffer,
                byte* __restrict info, size_t p)
        {
                *info = bool(p);
                if (p) *buffer = palette[p];
        }
        static constexpr bool DRAW_BACKDROP = false;
};
struct P2Policy {
        static byte readNameTable(const V9990VRAM& vram, unsigned addr) {
                return vram.readVRAMDirect(addr);
        }
        static byte readPatternTable(const V9990VRAM& vram, unsigned addr) {
                return vram.readVRAMBx(addr);
        }
        static byte readSpriteAttr(const V9990VRAM& vram, unsigned addr) {
                return vram.readVRAMDirect(addr);
        }
        static unsigned spritePatOfst(byte spriteNo, byte spriteY) {
                return (256 * (((spriteNo & 0xE0) >> 1) + spriteY))
                     + (  8 *  (spriteNo & 0x1F));
        }
        static void draw1(
                std::span<const Pixel, 16> palette, Pixel* __restrict buffer,
                byte* __restrict info, size_t p)
        {
                *info = bool(p);
                *buffer = palette[p];
        }
        static constexpr bool DRAW_BACKDROP = true;
        static constexpr unsigned SCREEN_WIDTH = 512;
        static constexpr unsigned IMAGE_WIDTH = 2 * SCREEN_WIDTH;
        static constexpr unsigned NAME_CHARS = IMAGE_WIDTH / 8;
        static constexpr unsigned PATTERN_CHARS = SCREEN_WIDTH / 8;
};
 
template<typename Policy, bool ALIGNED>
static unsigned getPatternAddress(
        V9990VRAM& vram, unsigned nameAddr, unsigned patternBase, unsigned x, unsigned y)
{
        assert(!ALIGNED || ((x & 7) == 0));
        unsigned patternNum = (Policy::readNameTable(vram, nameAddr + 0) +
                               Policy::readNameTable(vram, nameAddr + 1) * 256) & 0x1FFF;
        constexpr auto PATTERN_PITCH = Policy::PATTERN_CHARS * 8 * (8 / 2);
        unsigned x2 = (patternNum % Policy::PATTERN_CHARS) * 4 + (ALIGNED ? 0 : ((x & 7) / 2));
        unsigned y2 = (patternNum / Policy::PATTERN_CHARS) * PATTERN_PITCH + y;
        return patternBase + y2 + x2;
}
 
template<typename Policy>
static constexpr unsigned nextNameAddr(unsigned addr)
{
        constexpr auto MASK = (2 * Policy::NAME_CHARS) - 1;
        return (addr & ~MASK) | ((addr + 2) & MASK);
}
 
template<typename Policy, bool CHECK_WIDTH>
static void draw2(
        V9990VRAM& vram, std::span<const Pixel, 16> palette, Pixel* __restrict& buffer, byte* __restrict& info,
        unsigned& address, int& width)
{
        byte data = Policy::readPatternTable(vram, address++);
        Policy::draw1(palette, buffer + 0, info + 0, data >> 4);
        if (!CHECK_WIDTH || (width != 1)) {
                Policy::draw1(palette, buffer + 1, info + 1, data & 0x0F);
        }
        width  -= 2;
        buffer += 2;
        info   += 2;
}
 
template<typename Policy>
static void renderPattern(
        V9990VRAM& vram, Pixel* __restrict buffer, std::span<byte> info_,
        Pixel bgCol, unsigned x, unsigned y,
        unsigned nameTable, unsigned patternBase,
        std::span<const Pixel, 16> palette0, std::span<const Pixel, 16> palette1)
{
        assert(x < Policy::IMAGE_WIDTH);
        auto width = narrow<int>(info_.size());
        if (width == 0) return;
        byte* info = info_.data();
 
        std::optional<ScopedAssign<Pixel>> col0, col1; // optimized away when not used
        if constexpr (Policy::DRAW_BACKDROP) {
                // Speedup drawing by temporarily replacing palette index 0.
                // OK because palette0 and palette1 never partially overlap, IOW either:
                // - palette0 == palette1           (fully overlap)
                // - abs(palette0 - palette1) >= 16 (no overlap at all)
                col0.emplace(*const_cast<Pixel*>(palette0.data()), bgCol);
                col1.emplace(*const_cast<Pixel*>(palette1.data()), bgCol);
        }
 
        unsigned nameAddr = nameTable + (((y / 8) * Policy::NAME_CHARS + (x / 8)) * 2);
        y = (y & 7) * Policy::NAME_CHARS * 2;
 
        if (x & 7) {
                unsigned address = getPatternAddress<Policy, false>(vram, nameAddr, patternBase, x, y);
                if (x & 1) {
                        byte data = Policy::readPatternTable(vram, address);
                        Policy::draw1((address & 1) ? palette1 : palette0, buffer, info, data & 0x0F);
                        ++address;
                        ++x;
                        ++buffer;
                        ++info;
                        --width;
                }
                while ((x & 7) && (width > 0)) {
                        draw2<Policy, true>(vram, (address & 1) ? palette1 : palette0, buffer, info, address, width);
                        x += 2;
                }
                nameAddr = nextNameAddr<Policy>(nameAddr);
        }
        assert((x & 7) == 0 || (width <= 0));
        while ((width & ~7) > 0) {
                unsigned address = getPatternAddress<Policy, true>(vram, nameAddr, patternBase, x, y);
                draw2<Policy, false>(vram, palette0, buffer, info, address, width);
                draw2<Policy, false>(vram, palette1, buffer, info, address, width);
                draw2<Policy, false>(vram, palette0, buffer, info, address, width);
                draw2<Policy, false>(vram, palette1, buffer, info, address, width);
                nameAddr = nextNameAddr<Policy>(nameAddr);
        }
        assert(width < 8);
        if (width > 0) {
                unsigned address = getPatternAddress<Policy, true>(vram, nameAddr, patternBase, x, y);
                do {
                        draw2<Policy, true>(vram, (address & 1) ? palette1 : palette0, buffer, info, address, width);
                } while (width > 0);
        }
}
 
template<typename Policy> // only used for P1
static void renderPattern2(
        V9990VRAM& vram, Pixel* buffer, std::span<byte, 256> info, Pixel bgCol, unsigned width1, unsigned width2,
        unsigned displayAX, unsigned displayAY, unsigned nameA, unsigned patternA, std::span<const Pixel, 16> palA,
        unsigned displayBX, unsigned displayBY, unsigned nameB, unsigned patternB, std::span<const Pixel, 16> palB)
{
        renderPattern<Policy>(
                vram, buffer, subspan(info, 0, width1), bgCol,
                displayAX, displayAY, nameA, patternA, palA, palA);
 
        buffer += width1;
        width2 -= width1;
        displayBX = (displayBX + width1) & 511;
 
        renderPattern<Policy>(
                vram, buffer, subspan(info, width1, width2), bgCol,
                displayBX, displayBY, nameB, patternB, palB, palB);
}
 
template<typename Policy>
static void renderSprites(
        V9990VRAM& vram, unsigned spritePatternTable, std::span<const Pixel, 64> palette64,
        Pixel* __restrict buffer, std::span<byte> info,
        int displayX, int displayEnd, unsigned displayY)
{
        constexpr unsigned spriteTable = 0x3FE00;
 
        // determine visible sprites
        std::array<int, 16 + 1> visibleSprites;
        int index = 0;
        int index_max = 16;
        for (auto sprite : xrange(125)) {
                unsigned spriteInfo = spriteTable + 4 * sprite;
                byte spriteY = Policy::readSpriteAttr(vram, spriteInfo) + 1;
                auto posY = narrow_cast<byte>(displayY - spriteY);
                if (posY < 16) {
                        if (byte attr = Policy::readSpriteAttr(vram, spriteInfo + 3);
                            attr & 0x10) {
                                // Invisible sprites do contribute towards the
                                // 16-sprites-per-line limit.
                                index_max--;
                        } else {
                                visibleSprites[index++] = sprite;
                        }
                        if (index == index_max) break;
                }
        }
        visibleSprites[index] = -1;
 
        // actually draw sprites
        for (unsigned sprite = 0; visibleSprites[sprite] != -1; ++sprite) {
                unsigned addr = spriteTable + 4 * visibleSprites[sprite];
                byte spriteAttr = Policy::readSpriteAttr(vram, addr + 3);
                bool front = (spriteAttr & 0x20) == 0;
                byte level = front ? 2 : 1;
                int spriteX = Policy::readSpriteAttr(vram, addr + 2);
                spriteX += 256 * (spriteAttr & 0x03);
                if (spriteX > 1008) spriteX -= 1024; // hack X coord into -16..1008
                byte spriteY  = Policy::readSpriteAttr(vram, addr + 0);
                byte spriteNo = Policy::readSpriteAttr(vram, addr + 1);
                spriteY = narrow_cast<byte>(displayY - (spriteY + 1));
                unsigned patAddr = spritePatternTable + Policy::spritePatOfst(spriteNo, spriteY);
                auto palette16 = subspan<16>(palette64, (spriteAttr >> 2) & 0x30);
                for (int x = 0; x < 16; x +=2) {
                        auto draw = [&](int xPos, size_t p) {
                                if ((displayX <= xPos) && (xPos < displayEnd)) {
                                        size_t xx = xPos - displayX;
                                        if (p) {
                                                if (info[xx] < level) {
                                                        buffer[xx] = palette16[p];
                                                }
                                                info[xx] = 2; // also if back-sprite is behind foreground
                                        }
                                }
                        };
                        byte data = Policy::readPatternTable(vram, patAddr++);
                        draw(spriteX + x + 0, data >> 4);
                        draw(spriteX + x + 1, data & 0x0F);
                }
        }
}
 
void V9990P1Converter::convertLine(
        std::span<Pixel> buf, unsigned displayX, unsigned displayY,
        unsigned displayYA, unsigned displayYB, bool drawSprites)
{
        Pixel* __restrict linePtr = buf.data();
        auto displayWidth = narrow<unsigned>(buf.size());
 
        unsigned prioX = vdp.getPriorityControlX();
        unsigned prioY = vdp.getPriorityControlY();
        if (displayY >= prioY) prioX = 0;
 
        unsigned displayAX = (displayX + vdp.getScrollAX()) & 511;
        unsigned displayBX = (displayX + vdp.getScrollBX()) & 511;
 
        // Configurable 'roll' only applies to layer A.
        // Layer B always rolls at 512 lines.
        unsigned rollMask = vdp.getRollMask(0x1FF);
        unsigned scrollAY = vdp.getScrollAY();
        unsigned scrollBY = vdp.getScrollBY();
        unsigned scrollAYBase = scrollAY & ~rollMask & 0x1FF;
        unsigned displayAY = scrollAYBase + ((displayYA + scrollAY) & rollMask);
        unsigned displayBY =                 (displayYB + scrollBY) & 0x1FF;
 
        unsigned displayEnd = displayX + displayWidth;
        unsigned end1 = std::max(0, narrow<int>(std::min(prioX, displayEnd)) - narrow<int>(displayX));
 
        std::array<byte, 256> info; // filled in later: 0->background, 1->foreground, 2->sprite (front or back)
 
        // background + backdrop color
        Pixel bgCol = palette64[vdp.getBackDropColor()];
        byte offset = vdp.getPaletteOffset();
        auto palA = subspan<16>(palette64, (offset & 0x03) << 4);
        auto palB = subspan<16>(palette64, (offset & 0x0C) << 2);
        renderPattern2<P1BackgroundPolicy>( // does not yet fill-in 'info'
                vram, linePtr, /*dummy*/info, bgCol, end1, displayWidth,
                displayBX, displayBY, 0x7E000, 0x40000, palB,
                displayAX, displayAY, 0x7C000, 0x00000, palA);
 
        // foreground + fill-in 'info'
        assert(displayWidth <= 256);
        renderPattern2<P1ForegroundPolicy>( // fills 'info' with '0' or '1'
                vram, linePtr, info, bgCol, end1, displayWidth,
                displayAX, displayAY, 0x7C000, 0x00000, palA,
                displayBX, displayBY, 0x7E000, 0x40000, palB);
 
        // combined back+front sprite plane
        if (drawSprites) {
                unsigned spritePatternTable = vdp.getSpritePatternAddress(V9990DisplayMode::P1);
                renderSprites<P1Policy>( // uses and updates 'info'
                        vram, spritePatternTable, palette64,
                        linePtr, info, displayX, displayEnd, displayY);
        }
}
 
void V9990P2Converter::convertLine(
        std::span<Pixel> buf, unsigned displayX, unsigned displayY,
        unsigned displayYA, bool drawSprites)
{
        Pixel* __restrict linePtr = buf.data();
        auto displayWidth = narrow<unsigned>(buf.size());
 
        unsigned displayAX = (displayX + vdp.getScrollAX()) & 1023;
 
        unsigned scrollY = vdp.getScrollAY();
        unsigned rollMask = vdp.getRollMask(0x1FF);
        unsigned scrollYBase = scrollY & ~rollMask & 0x1FF;
        unsigned displayAY = scrollYBase + ((displayYA + scrollY) & rollMask);
 
        unsigned displayEnd = displayX + displayWidth;
 
        // image plane + backdrop color + fill-in 'info'
        assert(displayWidth <= 512);
        std::array<byte, 512> info; // filled in later: 0->background, 1->foreground, 2->sprite (front or back)
        Pixel bgCol = palette64[vdp.getBackDropColor()];
        byte offset = vdp.getPaletteOffset();
        auto palette0 = subspan<16>(palette64, (offset & 0x03) << 4);
        auto palette1 = subspan<16>(palette64, (offset & 0x0C) << 2);
        renderPattern<P2Policy>(
                vram, linePtr, subspan(info, 0, displayWidth), bgCol,
                displayAX, displayAY, 0x7C000, 0x00000, palette0, palette1);
 
        // combined back+front sprite plane
        if (drawSprites) {
                unsigned spritePatternTable = vdp.getSpritePatternAddress(V9990DisplayMode::P2);
                renderSprites<P2Policy>(
                        vram, spritePatternTable, palette64,
                        linePtr, info, displayX, displayEnd, displayY);
        }
}
 
} // namespace openmsx