/* Baremetal Risc-V USB <=> Amiga Joystick/Mouse HID converter. 
 * March 2026 - Anders Holck
 * This software has no license. If you choose to use, please include my name :)
*/

#include "amiga_hw.h"
#include "usb_dwc2.h"

#define GPIOA_EXT_PORTA 0x03020050

// GPIOA Bit Mappings (From PINS.md)
#define BIT_JOY1_FIRE  28
#define BIT_JOY1_UP    29
#define BIT_JOY1_DOWN  14
#define BIT_JOY1_LEFT  15
#define BIT_JOY1_RIGHT 16

#define BIT_JOY2_FIRE  17
#define BIT_JOY2_UP    18
#define BIT_JOY2_DOWN  19
#define BIT_JOY2_LEFT  20
#define BIT_JOY2_RIGHT 21

#define BIT_MOUSE_H_P  22
#define BIT_MOUSE_V_P  23
#define BIT_MOUSE_H_D  24
#define BIT_MOUSE_V_D  25
#define BIT_MOUSE_BT1  26
#define BIT_MOUSE_BT2  27

static uint8_t last_h_pulse = 0;
static uint8_t last_v_pulse = 0;

void amiga_hw_poll(amiga_input_t *input) {
    uint32_t val = read32(GPIOA_EXT_PORTA);

    // 1. Joystick 1 (Active Low - Amiga pulls to GND)
    input->joy1 = 0;
    if (!(val & (1 << BIT_JOY1_UP)))    input->joy1 |= (1 << 0);
    if (!(val & (1 << BIT_JOY1_DOWN)))  input->joy1 |= (1 << 1);
    if (!(val & (1 << BIT_JOY1_LEFT)))  input->joy1 |= (1 << 2);
    if (!(val & (1 << BIT_JOY1_RIGHT))) input->joy1 |= (1 << 3);
    if (!(val & (1 << BIT_JOY1_FIRE)))  input->joy1 |= (1 << 4);

    // 2. Joystick 2
    input->joy2 = 0;
    if (!(val & (1 << BIT_JOY2_UP)))    input->joy2 |= (1 << 0);
    if (!(val & (1 << BIT_JOY2_DOWN)))  input->joy2 |= (1 << 1);
    if (!(val & (1 << BIT_JOY2_LEFT)))  input->joy2 |= (1 << 2);
    if (!(val & (1 << BIT_JOY2_RIGHT))) input->joy2 |= (1 << 3);
    if (!(val & (1 << BIT_JOY2_FIRE)))  input->joy2 |= (1 << 4);

    // 3. Mouse Buttons
    input->buttons = 0;
    if (!(val & (1 << BIT_MOUSE_BT1)))  input->buttons |= (1 << 0);
    if (!(val & (1 << BIT_MOUSE_BT2)))  input->buttons |= (1 << 1);

    // 4. Mouse Quadrature Decoding (Simplified)
    // Amiga Mouse uses 2 pulses per axis (Clock/Data or Phase A/B)
    // Here we treat H-Pulse and V-Pulse as "clocks" and H-Dir/V-Dir as "direction"
    uint8_t curr_h_pulse = (val >> BIT_MOUSE_H_P) & 1;
    uint8_t curr_v_pulse = (val >> BIT_MOUSE_V_P) & 1;

    input->mouse_x = 0;
    if (curr_h_pulse != last_h_pulse) {
        uint8_t h_dir = (val >> BIT_MOUSE_H_D) & 1;
        input->mouse_x = (h_dir == curr_h_pulse) ? 1 : -1;
        last_h_pulse = curr_h_pulse;
    }

    input->mouse_y = 0;
    if (curr_v_pulse != last_v_pulse) {
        uint8_t v_dir = (val >> BIT_MOUSE_V_D) & 1;
        input->mouse_y = (v_dir == curr_v_pulse) ? 1 : -1;
        last_v_pulse = curr_v_pulse;
    }
}