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refactor(joystick): unify GameSir packet parsing with packet/payload offsets, fix field byte indexing and standardize length checks

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This commit is contained in:
chenzw
2026-02-03 19:10:10 +08:00
committed by Sam Lantinga
parent e087de5741
commit 8272699901
1 changed files with 69 additions and 62 deletions
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131
src/joystick/hidapi/SDL_hidapi_gamesir.c
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@@ -648,15 +648,17 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
return;
}
int packet_size = size;
const Uint8 *packet = data;
// Check packet format: it may include a report ID (0x43) as the first byte
// Actual packet format: 43 a1 c8 [button data...]
// If the first byte is 0x43, the second is 0xA1 and the third is 0xC8, skip the report ID
int packet_size = size;
if (size >= 3 && data[0] == 0x43 && data[1] == GAMESIR_PACKET_HEADER_0 && data[2] == GAMESIR_PACKET_HEADER_1_GAMEPAD) {
// Packet contains a report ID; skip the first byte
if (size >= 3 && packet[0] == 0x43 && packet[1] == GAMESIR_PACKET_HEADER_0 && packet[2] == GAMESIR_PACKET_HEADER_1_GAMEPAD) {
// Packet contains a report ID; skip it for indexing and size checks
packet_size = size - 1;
} else if (size >= 2 && data[0] == GAMESIR_PACKET_HEADER_0 && data[1] == GAMESIR_PACKET_HEADER_1_GAMEPAD) {
packet = data + 1;
} else if (size >= 2 && packet[0] == GAMESIR_PACKET_HEADER_0 && packet[1] == GAMESIR_PACKET_HEADER_1_GAMEPAD) {
// Standard format: no report ID, header bytes directly
packet_size = size;
} else {
@@ -664,15 +666,20 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
return;
}
const int header_size = 2;
const int payload_size = packet_size - header_size;
const Uint8 *payload = packet + header_size;
const Uint8 *last = ctx->last_state + header_size;
bool is_initial_packet = (ctx->last_state[0] == 0 && ctx->last_state[1] == 0 && ctx->last_state[2] == 0 && ctx->last_state[3] == 0);
const int min_packet_size = ctx->sensors_enabled ? 29 : 17;
if (packet_size < min_packet_size) {
const int min_payload_size = ctx->sensors_enabled ? 26 : 14;
if (payload_size < min_payload_size) {
return;
}
if (ctx->last_state[3] != data[3]) {
Uint8 buttons = data[3];
if (last[0] != payload[0]) {
Uint8 buttons = payload[0];
// BTN1: A B C X Y Z L1 R1
// Use bitwise operations to check whether each button is pressed
// buttons & BTN_A returns the value of BTN_A (if pressed) or 0 (if not pressed)
@@ -684,10 +691,10 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
SDL_SendJoystickButton(timestamp, joystick, SDL_GAMEPAD_BUTTON_RIGHT_SHOULDER, buttons & BTN_R1);
}
if (ctx->last_state[4] != data[4]) {
Uint8 buttons = data[4];
if (last[1] != payload[1]) {
Uint8 buttons = payload[1];
// BTN2: L2 R2 SELECT START HOME L3 R3 CAPTURE
// Note: L2/R2 appear as digital buttons in data[4], but their actual analog values are in data[15]/data[16].
// Note: L2/R2 appear as digital buttons in payload[1], but their actual analog values are in payload[12]/payload[13].
// Only handle the other buttons here; trigger analog values are processed later in the code.
SDL_SendJoystickButton(timestamp, joystick, SDL_GAMEPAD_BUTTON_BACK, buttons & BTN_SELECT);
SDL_SendJoystickButton(timestamp, joystick, SDL_GAMEPAD_BUTTON_START, buttons & BTN_START);
@@ -697,8 +704,8 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
SDL_SendJoystickButton(timestamp, joystick, SDL_GAMEPAD_BUTTON_MISC1, buttons & BTN_CAPTURE);
}
if (ctx->last_state[5] != data[5]) {
Uint8 buttons = data[5];
if (last[2] != payload[2]) {
Uint8 buttons = payload[2];
// BTN3: UP DOWN LEFT RIGHT M MUTE L4 R4
// Handle the directional pad (D-pad)
Uint8 hat = SDL_HAT_CENTERED;
@@ -731,8 +738,8 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
SDL_SendJoystickButton(timestamp, joystick, SDL_GAMEPAD_BUTTON_MISC2, buttons & BTN_MUTE);
}
if (ctx->last_state[6] != data[6]) {
Uint8 buttons = data[6];
if (last[3] != payload[3]) {
Uint8 buttons = payload[3];
// BTN4: L5 R5 L6 R6 L7 R7 L8 R8
SDL_SendJoystickButton(timestamp, joystick, SDL_GAMEPAD_BUTTON_LEFT_PADDLE2, buttons & BTN_L5);
SDL_SendJoystickButton(timestamp, joystick, SDL_GAMEPAD_BUTTON_RIGHT_PADDLE2, buttons & BTN_R5);
@@ -750,13 +757,13 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
SDL_SendJoystickAxis(timestamp, joystick, SDL_GAMEPAD_AXIS_RIGHTY, 0);
} else {
// Left stick handling
// Left stick: bytes 7-10 (16-bit values)
// Bytes 7-8: X axis (Hi/Low combined into a signed 16-bit value, e.g. 0x7df6)
// Bytes 9-10: Y axis (Hi/Low combined into a signed 16-bit value)
if (size >= 11) {
// Combine bytes 7-8 into a 16-bit value, e.g.: data[7]=0x7d, data[8]=0xf6 -> 0x7df6
Uint16 raw_x_unsigned = ((Uint16)data[7] << 8) | data[8];
Uint16 raw_y_unsigned = ((Uint16)data[9] << 8) | data[10];
// Left stick: payload bytes 4-7 (16-bit values)
// Bytes 4-5: X axis (Hi/Low combined into a signed 16-bit value, e.g. 0x7df6)
// Bytes 6-7: Y axis (Hi/Low combined into a signed 16-bit value)
if (payload_size >= 8) {
// Combine bytes 4-5 into a 16-bit value, e.g.: payload[4]=0x7d, payload[5]=0xf6 -> 0x7df6
Uint16 raw_x_unsigned = ((Uint16)payload[4] << 8) | payload[5];
Uint16 raw_y_unsigned = ((Uint16)payload[6] << 8) | payload[7];
// Interpret the unsigned 16-bit value as a signed 16-bit value
Sint16 raw_x = (Sint16)raw_x_unsigned;
@@ -767,8 +774,8 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
left_x = raw_x;
left_y = -raw_y;
Uint16 last_raw_x_unsigned = ((Uint16)ctx->last_state[7] << 8) | ctx->last_state[8];
Uint16 last_raw_y_unsigned = ((Uint16)ctx->last_state[9] << 8) | ctx->last_state[10];
Uint16 last_raw_x_unsigned = ((Uint16)last[4] << 8) | last[5];
Uint16 last_raw_y_unsigned = ((Uint16)last[6] << 8) | last[7];
Sint16 last_raw_x = (Sint16)last_raw_x_unsigned;
Sint16 last_raw_y = (Sint16)last_raw_y_unsigned;
bool raw_changed = (raw_x != last_raw_x || raw_y != last_raw_y);
@@ -792,14 +799,14 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
}
// Right stick handling
// Right stick: bytes 11-14 (16-bit values)
// Bytes 11-12: X axis (Hi/Low combined into a signed 16-bit value)
// Bytes 13-14: Y axis (Hi/Low combined into a signed 16-bit value)
if (size >= 15) {
// Combine bytes 11-12 into a 16-bit value
Uint16 raw_x_unsigned = ((Uint16)data[11] << 8) | data[12];
// Combine bytes 13-14 into a 16-bit value
Uint16 raw_y_unsigned = ((Uint16)data[13] << 8) | data[14];
// Right stick: payload bytes 8-11 (16-bit values)
// Bytes 8-9: X axis (Hi/Low combined into a signed 16-bit value)
// Bytes 10-11: Y axis (Hi/Low combined into a signed 16-bit value)
if (payload_size >= 12) {
// Combine bytes 8-9 into a 16-bit value
Uint16 raw_x_unsigned = ((Uint16)payload[8] << 8) | payload[9];
// Combine bytes 10-11 into a 16-bit value
Uint16 raw_y_unsigned = ((Uint16)payload[10] << 8) | payload[11];
// Interpret the unsigned 16-bit value as a signed 16-bit value
Sint16 raw_x = (Sint16)raw_x_unsigned;
@@ -810,8 +817,8 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
right_x = raw_x;
right_y = -raw_y;
Uint16 last_raw_x_unsigned = ((Uint16)ctx->last_state[11] << 8) | ctx->last_state[12];
Uint16 last_raw_y_unsigned = ((Uint16)ctx->last_state[13] << 8) | ctx->last_state[14];
Uint16 last_raw_x_unsigned = ((Uint16)last[8] << 8) | last[9];
Uint16 last_raw_y_unsigned = ((Uint16)last[10] << 8) | last[11];
Sint16 last_raw_x = (Sint16)last_raw_x_unsigned;
Sint16 last_raw_y = (Sint16)last_raw_y_unsigned;
bool raw_changed = (raw_x != last_raw_x || raw_y != last_raw_y);
@@ -835,35 +842,35 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
}
// Handle trigger axes
// Protocol: L2 (byte 15) - analog left trigger 0-255, 0 = released, 255 = pressed
// R2 (byte 16) - analog right trigger 0-255, 0 = released, 255 = pressed
// Protocol: L2 (payload byte 12) - analog left trigger 0-255, 0 = released, 255 = pressed
// R2 (payload byte 13) - analog right trigger 0-255, 0 = released, 255 = pressed
// SDL range: 0-32767 (0 = released, 32767 = fully pressed)
// Linear mapping: 0-255 -> 0-32767
if (ctx->last_state[15] != data[15]) {
axis = (Sint16)(((int)data[15] * 255) - 32767);
if (last[12] != payload[12]) {
axis = (Sint16)(((int)payload[12] * 255) - 32767);
SDL_SendJoystickAxis(timestamp, joystick, SDL_GAMEPAD_AXIS_LEFT_TRIGGER, axis);
}
if (ctx->last_state[16] != data[16]) {
axis = (Sint16)(((int)data[16] * 255) - 32767);
if (last[13] != payload[13]) {
axis = (Sint16)(((int)payload[13] * 255) - 32767);
SDL_SendJoystickAxis(timestamp, joystick, SDL_GAMEPAD_AXIS_RIGHT_TRIGGER, axis);
}
}
if (ctx->sensors_enabled && !is_initial_packet && size >= 29) {
if (ctx->sensors_enabled && !is_initial_packet && payload_size >= 26) {
Uint64 sensor_timestamp;
float values[3];
sensor_timestamp = ctx->sensor_timestamp_ns;
ctx->sensor_timestamp_ns += ctx->sensor_timestamp_step_ns;
// Accelerometer data (bytes 17-22)
// Bytes 17-18: Acc X (Hi/Low combined into a signed 16-bit value)
// Bytes 19-20: Acc Y (Hi/Low combined into a signed 16-bit value)
// Bytes 21-22: Acc Z (Hi/Low combined into a signed 16-bit value)
Uint16 acc_x_unsigned = ((Uint16)data[17] << 8) | data[18];
Uint16 acc_y_unsigned = ((Uint16)data[19] << 8) | data[20];
Uint16 acc_z_unsigned = ((Uint16)data[21] << 8) | data[22];
// Accelerometer data (payload bytes 14-19)
// Bytes 14-15: Acc X (Hi/Low combined into a signed 16-bit value)
// Bytes 16-17: Acc Y (Hi/Low combined into a signed 16-bit value)
// Bytes 18-19: Acc Z (Hi/Low combined into a signed 16-bit value)
Uint16 acc_x_unsigned = ((Uint16)payload[14] << 8) | payload[15];
Uint16 acc_y_unsigned = ((Uint16)payload[16] << 8) | payload[17];
Uint16 acc_z_unsigned = ((Uint16)payload[18] << 8) | payload[19];
// Convert the unsigned 16-bit values to signed 16-bit values
Sint16 acc_x = (Sint16)acc_x_unsigned;
@@ -877,13 +884,13 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
values[2] = (float)acc_z * ctx->accelScale; // Acc Z
SDL_SendJoystickSensor(timestamp, joystick, SDL_SENSOR_ACCEL, sensor_timestamp, values, 3);
// Gyroscope data (bytes 23-28)
// Bytes 23-24: Gyro X (Hi/Low combined into a signed 16-bit value)
// Bytes 25-26: Gyro Y (Hi/Low combined into a signed 16-bit value)
// Bytes 27-28: Gyro Z (Hi/Low combined into a signed 16-bit value)
Uint16 gyro_x_unsigned = ((Uint16)data[23] << 8) | data[24];
Uint16 gyro_y_unsigned = ((Uint16)data[25] << 8) | data[26];
Uint16 gyro_z_unsigned = ((Uint16)data[27] << 8) | data[28];
// Gyroscope data (payload bytes 20-25)
// Bytes 20-21: Gyro X (Hi/Low combined into a signed 16-bit value)
// Bytes 22-23: Gyro Y (Hi/Low combined into a signed 16-bit value)
// Bytes 24-25: Gyro Z (Hi/Low combined into a signed 16-bit value)
Uint16 gyro_x_unsigned = ((Uint16)payload[20] << 8) | payload[21];
Uint16 gyro_y_unsigned = ((Uint16)payload[22] << 8) | payload[23];
Uint16 gyro_z_unsigned = ((Uint16)payload[24] << 8) | payload[25];
// Convert the unsigned 16-bit values to signed 16-bit values
Sint16 gyro_x = (Sint16)gyro_x_unsigned;
@@ -900,12 +907,12 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
values[2] = (float)gyro_z * ctx->gyroScale; // Gyro Z (Roll)
SDL_SendJoystickSensor(timestamp, joystick, SDL_SENSOR_GYRO, sensor_timestamp, values, 3);
}
if (size >= 35) {
Uint16 l_touchpad_x = ((Uint16)data[29] << 4) | ((data[30] >> 4) & 0x0F);
Uint16 l_touchpad_y = ((Uint16)(data[30] & 0x0F) << 8) | data[31];
if (payload_size >= 32) {
Uint16 l_touchpad_x = ((Uint16)payload[26] << 4) | ((payload[27] >> 4) & 0x0F);
Uint16 l_touchpad_y = ((Uint16)(payload[27] & 0x0F) << 8) | payload[28];
Uint16 r_touchpad_x = ((Uint16)data[32] << 4) | ((data[33] >> 4) & 0x0F);
Uint16 r_touchpad_y = ((Uint16)(data[33] & 0x0F) << 8) | data[34];
Uint16 r_touchpad_x = ((Uint16)payload[29] << 4) | ((payload[30] >> 4) & 0x0F);
Uint16 r_touchpad_y = ((Uint16)(payload[30] & 0x0F) << 8) | payload[31];
(void)l_touchpad_x;
(void)l_touchpad_y;
@@ -913,7 +920,7 @@ static void HIDAPI_DriverGameSir_HandleStatePacket(SDL_Joystick *joystick, SDL_D
(void)r_touchpad_y;
}
SDL_memcpy(ctx->last_state, data, SDL_min(size, sizeof(ctx->last_state)));
SDL_memcpy(ctx->last_state, packet, SDL_min(packet_size, sizeof(ctx->last_state)));
}