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Merged
maxvdec merged 1 commit into from
Jul 12, 2026
Merged

Add fullscreen display and SDL gamepad support to emulator #1

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4 changes: 3 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -142,7 +142,9 @@ usage: e16emu [-s] [--load-address addr] [--scale n] program.bin

- `-s`: enable debugger mode.
- `--load-address`: choose where the binary is loaded.
- `--scale`: set the emulator display scale.
- `--scale`: set the emulator display scale used when SDL creates the fullscreen window.
- The emulator opens fullscreen by default and letterboxes the 320x180 display.
- Gamepads are supported for up to two players. D-pads and left/right sticks map to directions; South/East/West/North map to A/B/X/Y; Start/Right Shoulder map to Start; Back/Left Shoulder map to Select.

### `e16dis`

Expand Down
13 changes: 12 additions & 1 deletion emulator/include/e16/sdl_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -35,16 +35,27 @@ class SdlHost {
SDL_AudioStream *audio = nullptr;
Apu *apuDevice = nullptr;
std::string errorText;
struct GamepadSlot {
SDL_JoystickID instanceId = 0;
SDL_Gamepad *gamepad = nullptr;
};

std::vector<float> audioBuffer;
std::vector<GamepadSlot> gamepads;
bool twoPlayerControls = false;
bool controlsKeyDown = false;

void close();
void showControls() const;
void openAvailableGamepads();
void openGamepad(SDL_JoystickID instanceId);
void closeGamepad(SDL_JoystickID instanceId);
void closeAllGamepads();
std::uint16_t gamepadPad(std::size_t player) const;
static void audioCallback(void *userdata, SDL_AudioStream *stream,
int additionalAmount, int totalAmount);
};

}
} // namespace e16

#endif
145 changes: 135 additions & 10 deletions emulator/src/sdl_host.cpp
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Original file line number Diff line number Diff line change
@@ -1,5 +1,8 @@
#include "e16/sdl_host.h"

#include <algorithm>
#include <cstdlib>

namespace e16 {

namespace {
Expand Down Expand Up @@ -49,7 +52,56 @@ std::uint16_t keyboardPad1() {
bool escapePressed() {
return SDL_GetKeyboardState(nullptr)[SDL_SCANCODE_ESCAPE];
}

std::uint16_t gamepadButtons(SDL_Gamepad *gamepad) {
if (!gamepad) {
return 0;
}

constexpr Sint16 AxisDeadZone = 12000;
std::uint16_t pad = 0;

const Sint16 leftX = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_LEFTX);
const Sint16 leftY = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_LEFTY);
const Sint16 rightX = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_RIGHTX);
const Sint16 rightY = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_RIGHTY);

pad |= (leftX > AxisDeadZone || rightX > AxisDeadZone) ? ButtonRight : 0;
pad |= (leftX < -AxisDeadZone || rightX < -AxisDeadZone) ? ButtonLeft : 0;
pad |= (leftY > AxisDeadZone || rightY > AxisDeadZone) ? ButtonDown : 0;
pad |= (leftY < -AxisDeadZone || rightY < -AxisDeadZone) ? ButtonUp : 0;

pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_DPAD_RIGHT)
? ButtonRight
: 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_DPAD_LEFT)
? ButtonLeft
: 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_DPAD_DOWN)
? ButtonDown
: 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_DPAD_UP) ? ButtonUp
: 0;
pad |=
SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_SOUTH) ? ButtonA : 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_EAST) ? ButtonB : 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_WEST) ? ButtonX : 0;
pad |=
SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_NORTH) ? ButtonY : 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_START) ? ButtonStart
: 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_BACK) ? ButtonSelect
: 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_LEFT_SHOULDER)
? ButtonSelect
: 0;
pad |= SDL_GetGamepadButton(gamepad, SDL_GAMEPAD_BUTTON_RIGHT_SHOULDER)
? ButtonStart
: 0;

return pad;
}
} // namespace

SdlHost::SdlHost() = default;

Expand All @@ -65,13 +117,14 @@ bool SdlHost::open(int scale, Apu &apu) {
return false;
}
window = SDL_CreateWindow("Ember-16", ScreenWidth * scale,
ScreenHeight * scale, 0);
ScreenHeight * scale, SDL_WINDOW_FULLSCREEN);
if (!window) {
errorText = SDL_GetError();
return false;
}
SDL_SetWindowFocusable(window, true);
SDL_RaiseWindow(window);
openAvailableGamepads();
renderer = SDL_CreateRenderer(window, nullptr);
if (!renderer) {
errorText = SDL_GetError();
Expand Down Expand Up @@ -110,6 +163,11 @@ bool SdlHost::poll(Memory &memory) {
if (event.type == SDL_EVENT_QUIT) {
return false;
}
if (event.type == SDL_EVENT_GAMEPAD_ADDED) {
openGamepad(event.gdevice.which);
} else if (event.type == SDL_EVENT_GAMEPAD_REMOVED) {
closeGamepad(event.gdevice.which);
}
}
const bool *keys = SDL_GetKeyboardState(nullptr);
if (keys[SDL_SCANCODE_F1] && !controlsKeyDown) {
Expand All @@ -119,8 +177,8 @@ bool SdlHost::poll(Memory &memory) {
if (escapePressed()) {
return false;
}
memory.inputPad0 = keyboardPad0();
memory.inputPad1 = twoPlayerControls ? keyboardPad1() : 0;
memory.inputPad0 = keyboardPad0() | gamepadPad(0);
memory.inputPad1 = (twoPlayerControls ? keyboardPad1() : 0) | gamepadPad(1);
return true;
}

Expand All @@ -141,14 +199,22 @@ void SdlHost::present(const Flame &flame) {
SDL_RenderPresent(renderer);
}

const std::string &SdlHost::error() const {
return errorText;
}
const std::string &SdlHost::error() const { return errorText; }

void SdlHost::showControls() const {
const char *message = twoPlayerControls
? "Player 1\nArrows: directions\nZ/X/A/S: A/B/X/Y\nEnter: Start Left Shift: Select\n\nPlayer 2\nI/J/K/L: Up/Left/Down/Right\n1/2/3/4: A/B/X/Y\n0: Start Right Shift: Select\n\nF1 opens this panel."
: "Player 1\nArrows: directions\nZ/X/A/S: A/B/X/Y\nEnter: Start Left Shift: Select\n\nPlayer 2 activates automatically when the game reads INPUT_PAD1.\n\nF1 opens this panel.";
const char *message =
twoPlayerControls
? "Player 1\nArrows or gamepad 1 sticks/D-pad: directions\nZ/X/A/S "
"or South/East/West/North: A/B/X/Y\nEnter/Start: Start Left "
"Shift/Back: Select\n\nPlayer 2\nI/J/K/L or gamepad 2 "
"sticks/D-pad: directions\n1/2/3/4 or South/East/West/North: "
"A/B/X/Y\n0/Start: Start Right Shift/Back: Select\n\nF1 opens "
"this panel."
: "Player 1\nArrows or gamepad 1 sticks/D-pad: directions\nZ/X/A/S "
"or South/East/West/North: A/B/X/Y\nEnter/Start: Start Left "
"Shift/Back: Select\n\nPlayer 2 activates automatically when the "
"game reads INPUT_PAD1 or when a second gamepad is "
"connected.\n\nF1 opens this panel.";
SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_INFORMATION, "Ember-16 Controls",
message, window);
}
Expand All @@ -166,13 +232,72 @@ void SdlHost::close() {
SDL_DestroyRenderer(renderer);
renderer = nullptr;
}
closeAllGamepads();
if (window) {
SDL_DestroyWindow(window);
window = nullptr;
}
apuDevice = nullptr;
}

void SdlHost::openAvailableGamepads() {
int count = 0;
SDL_JoystickID *ids = SDL_GetGamepads(&count);
if (!ids) {
return;
}
for (int i = 0; i < count; i++) {
openGamepad(ids[i]);
}
SDL_free(ids);
}

void SdlHost::openGamepad(SDL_JoystickID instanceId) {
auto existing = std::find_if(gamepads.begin(), gamepads.end(),
[instanceId](const GamepadSlot &slot) {
return slot.instanceId == instanceId;
});
if (existing != gamepads.end() || gamepads.size() >= 2 ||
!SDL_IsGamepad(instanceId)) {
return;
}

SDL_Gamepad *gamepad = SDL_OpenGamepad(instanceId);
if (!gamepad) {
return;
}
gamepads.push_back({instanceId, gamepad});
if (gamepads.size() > 1) {
enableTwoPlayerControls();
}
}

void SdlHost::closeGamepad(SDL_JoystickID instanceId) {
auto removed = std::remove_if(gamepads.begin(), gamepads.end(),
[instanceId](GamepadSlot &slot) {
if (slot.instanceId != instanceId) {
return false;
}
SDL_CloseGamepad(slot.gamepad);
return true;
});
gamepads.erase(removed, gamepads.end());

@chatgpt-codex-connector chatgpt-codex-connector Bot Jul 11, 2026

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P2 Badge Preserve gamepad player slots on disconnect

When the first of two connected gamepads is unplugged, this erase compacts the vector, while gamepadPad() treats vector index 0/1 as player 1/2. In a two-player session with a transient disconnect of player 1's controller, the remaining player 2 controller starts driving player 1 and player 2 reads as disconnected; replugging the original controller then assigns it to player 2. Keep fixed slots or replace the removed slot with an empty entry so hotplugging does not silently swap player assignments.

Useful? React with 👍 / 👎.

}

void SdlHost::closeAllGamepads() {
for (GamepadSlot &slot : gamepads) {
SDL_CloseGamepad(slot.gamepad);
}
gamepads.clear();
}

std::uint16_t SdlHost::gamepadPad(std::size_t player) const {
if (player >= gamepads.size()) {
return 0;
}
return gamepadButtons(gamepads[player].gamepad);
}

void SdlHost::audioCallback(void *userdata, SDL_AudioStream *stream,
int additionalAmount, int totalAmount) {
(void)totalAmount;
Expand All @@ -191,4 +316,4 @@ void SdlHost::audioCallback(void *userdata, SDL_AudioStream *stream,
static_cast<int>(host->audioBuffer.size() * sizeof(float)));
}

}
} // namespace e16
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