add display

evanwporter · evanwporter · commit 36cb58fea82e · 2026-04-08T12:06:18.000-07:00
diff --git a/cores/gba/sim/include/gpu.hpp b/cores/gba/sim/include/gpu.hpp
@@ -0,0 +1,7 @@
+#pragma once
+
+#include "gba.hpp"
+
+void render_frame(GameboyAdvanceHarness& gba, u32 framebuffer[160][240]);
+
+void run_with_display(GameboyAdvanceHarness& gba);
diff --git a/cores/gba/sim/src/CMakeLists.txt b/cores/gba/sim/src/CMakeLists.txt
@@ -1,3 +1,4 @@
 target_sources(GameboyAdvanceHarness 
     PRIVATE 
-        ${CMAKE_CURRENT_SOURCE_DIR}/gba.cpp)
+        ${CMAKE_CURRENT_SOURCE_DIR}/gba.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/gpu.cpp)
diff --git a/cores/gba/sim/src/gpu.cpp b/cores/gba/sim/src/gpu.cpp
@@ -0,0 +1,222 @@
+// Code taken w/ modifications from https://github.com/RidgeX/ygba
+// Copyright (c) 2021 Ridge Shrubsall
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include "gpu.hpp"
+#include "gba.hpp"
+#include <iostream>
+
+#define BIT(x, i) (((x) >> (i)) & 1)
+#define BITS(x, i, j) (((x) >> (i)) & ((1 << ((j) - (i) + 1)) - 1))
+
+#define SCREEN_WIDTH 240
+#define SCREEN_HEIGHT 160
+
+static u32 rgb555_to_rgb888(u16 pixel) {
+    int red = BITS(pixel, 0, 4);
+    int green = BITS(pixel, 5, 9);
+    int blue = BITS(pixel, 10, 14);
+
+    red = (red << 3) | (red >> 2);
+    green = (green << 3) | (green >> 2);
+    blue = (blue << 3) | (blue >> 2);
+
+    return 0xff << 24 | blue << 16 | green << 8 | red;
+}
+
+static bool read_bitmap_pixel(GameboyAdvanceHarness& gba, int x, int y, int mode, u16& out) {
+    auto vram = gba.get_top().rootp->GameboyAdvance__DOT__VRAM__DOT__mem;
+    auto io = gba.get_top().rootp->GameboyAdvance__DOT__IO__DOT__mem;
+
+    int w = (mode == 5 ? 160 : 240);
+    int h = (mode == 5 ? 128 : 160);
+
+    if (x >= w || y >= h)
+        return false;
+
+    if (mode == 3) {
+        u32 addr = (y * 240 + x) * 2;
+        out = *(u16*)&vram[addr];
+        return true;
+    }
+
+    if (mode == 4) {
+        bool page = (io[0x000] & 0x10); // DISPCNT bit 4
+        u32 base = page ? 0xA000 : 0x0000;
+
+        uint8_t index = vram[base + y * 240 + x];
+        if (index == 0)
+            return false;
+
+        auto palette = gba.get_top().rootp->GameboyAdvance__DOT__Palette__DOT__mem;
+        out = *(u16*)&palette[index * 2];
+        return true;
+    }
+
+    if (mode == 5) {
+        bool page = (io[0x000] & 0x10);
+        u32 base = page ? 0xA000 : 0x0000;
+
+        u32 addr = base + (y * 160 + x) * 2;
+        out = *(u16*)&vram[addr];
+        return true;
+    }
+
+    return false;
+}
+
+void render_frame(GameboyAdvanceHarness& gba, u32 framebuffer[160][240]) {
+
+    auto io = gba.get_top().rootp->GameboyAdvance__DOT__IO__DOT__mem;
+    int mode = io[0] & 0x7; // DISPCNT
+
+    for (int y = 0; y < 160; y++) {
+        for (int x = 0; x < 240; x++) {
+            u16 pixel;
+
+            if (read_bitmap_pixel(gba, x, y, mode, pixel)) {
+                framebuffer[y][x] = rgb555_to_rgb888(pixel);
+            } else {
+                framebuffer[y][x] = 0xFF000000; // black
+            }
+        }
+    }
+}
+
+#include <SDL2/SDL.h>
+#include <cstdint>
+
+class SDLDisplay {
+public:
+    static constexpr int WIDTH = 240;
+    static constexpr int HEIGHT = 160;
+
+    bool init(int scale = 3) {
+        if (SDL_Init(SDL_INIT_VIDEO) != 0) {
+            return false;
+        }
+
+        window = SDL_CreateWindow(
+            "GBA",
+            SDL_WINDOWPOS_CENTERED,
+            SDL_WINDOWPOS_CENTERED,
+            WIDTH * scale,
+            HEIGHT * scale,
+            0);
+
+        renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
+
+        texture = SDL_CreateTexture(
+            renderer,
+            SDL_PIXELFORMAT_ARGB8888,
+            SDL_TEXTUREACCESS_STREAMING,
+            WIDTH,
+            HEIGHT);
+
+        return window && renderer && texture;
+    }
+
+    void draw(uint32_t framebuffer[HEIGHT][WIDTH]) {
+        SDL_UpdateTexture(texture, nullptr, framebuffer, WIDTH * sizeof(uint32_t));
+
+        SDL_RenderClear(renderer);
+        SDL_RenderCopy(renderer, texture, nullptr, nullptr);
+        SDL_RenderPresent(renderer);
+    }
+
+    bool process_events() {
+        SDL_Event e;
+        while (SDL_PollEvent(&e)) {
+            if (e.type == SDL_QUIT)
+                return false;
+        }
+        return true;
+    }
+
+    ~SDLDisplay() {
+        if (texture)
+            SDL_DestroyTexture(texture);
+        if (renderer)
+            SDL_DestroyRenderer(renderer);
+        if (window)
+            SDL_DestroyWindow(window);
+        SDL_Quit();
+    }
+
+private:
+    SDL_Window* window = nullptr;
+    SDL_Renderer* renderer = nullptr;
+    SDL_Texture* texture = nullptr;
+};
+
+void run_with_display(GameboyAdvanceHarness& gba) {
+    const int WIDTH = 240;
+    const int HEIGHT = 160;
+    const int SCALE = 3;
+    const int CYCLES_PER_FRAME = 280896;
+
+    if (SDL_Init(SDL_INIT_VIDEO) != 0) {
+        std::cerr << "SDL init failed\n";
+        return;
+    }
+
+    SDL_Window* window = SDL_CreateWindow(
+        "GBA",
+        SDL_WINDOWPOS_CENTERED,
+        SDL_WINDOWPOS_CENTERED,
+        WIDTH * SCALE,
+        HEIGHT * SCALE,
+        0);
+
+    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
+    SDL_Texture* texture = SDL_CreateTexture(
+        renderer,
+        SDL_PIXELFORMAT_ARGB8888,
+        SDL_TEXTUREACCESS_STREAMING,
+        WIDTH,
+        HEIGHT);
+
+    if (!window || !renderer || !texture) {
+        std::cerr << "SDL setup failed\n";
+        return;
+    }
+
+    uint32_t framebuffer[HEIGHT][WIDTH];
+    int cycle_counter = 0;
+    bool running = true;
+
+    while (running) {
+        // --- Handle events ---
+        SDL_Event e;
+        while (SDL_PollEvent(&e)) {
+            if (e.type == SDL_QUIT) {
+                running = false;
+            }
+        }
+
+        // --- Run emulation ---
+        gba.tick();
+        cycle_counter++;
+
+        // --- Render once per frame ---
+        if (cycle_counter >= CYCLES_PER_FRAME) {
+            cycle_counter = 0;
+
+            render_frame(gba, framebuffer);
+
+            SDL_UpdateTexture(texture, nullptr, framebuffer, WIDTH * sizeof(uint32_t));
+
+            SDL_RenderClear(renderer);
+            SDL_RenderCopy(renderer, texture, nullptr, nullptr);
+            SDL_RenderPresent(renderer);
+
+            // Optional: cap to ~60 FPS
+            SDL_Delay(16);
+        }
+    }
+
+    SDL_DestroyTexture(texture);
+    SDL_DestroyRenderer(renderer);
+    SDL_DestroyWindow(window);
+    SDL_Quit();
+}
diff --git a/cores/gba/tests/arm.gba/test_arm.cpp b/cores/gba/tests/arm.gba/test_arm.cpp
@@ -8,6 +8,8 @@
 #include <gtest/gtest.h>
 
 #include "gba.hpp"
+#include "gpu.hpp"
+
 #include "util/decode.hpp"
 #include "util/test_config.hpp"
 #include "util/util.hpp"
@@ -409,6 +411,8 @@ TEST(ARM_GBA_Tests, CPUInstrsAll) {
                 harness.get_top().rootp->GameboyAdvance__DOT__cpu_inst__DOT__regs.__PVT__common.__PVT__r2 = 436207618;
 
             if (step_index == 1331) {
+                run_with_display(harness);
+
                 // TODO: Implement display
                 break;
             }
