bus.h

 
#pragma once
 
#include <stddef.h>
#include <stdint.h>
 
#include <joybus/target.h>
 
struct joybus;

#define JOYBUS_FREQ_NOMINAL             250000

#define JOYBUS_FREQ_N64_CONSOLE         244141 // PIF-NUS @ 15.625MHz / 64

#define JOYBUS_FREQ_N64_EXTJOY          JOYBUS_FREQ_N64_CONSOLE // SECCLK @ 1.953125MHz / 8

#define JOYBUS_FREQ_N64_CONTROLLER      250000 // CNT-NUS @ 2MHz / 8

#define JOYBUS_FREQ_N64_VRU             250000 // VCI-NUS @ 4MHz / 16

#define JOYBUS_FREQ_GCN_CONSOLE         202500 // Flipper @ 162MHz / 800

#define JOYBUS_FREQ_GCN_CONTROLLER      250000 // CNT-DOL @ 4MHz / 16

#define JOYBUS_FREQ_WAVEBIRD_RECEIVER   225000 // WCRX-DOL @ 28.8MHz / 128

#define JOYBUS_FREQ_WII_CONSOLE         202500 // Hollywood @ 243MHz / 1200

#define JOYBUS_FREQ_GCN_GBA_CABLE       262144 // CPU-AGB @ 16.777216MHz / 64

#define JOYBUS_INTER_TRANSFER_DELAY_US  80

#define JOYBUS_REPLY_TIMEOUT_US         64

#define JOYBUS_BUS_IDLE_US              100

#define JOYBUS_BLOCK_SIZE               64

#define JOYBUS(bus) ((struct joybus *)(bus))

enum joybus_mode {
  JOYBUS_MODE_HOST,

  JOYBUS_MODE_TARGET,
};

typedef void (*joybus_transfer_cb)(struct joybus *bus, int status, void *user_data);
 
// API for a Joybus backend - internal use only
struct joybus_api {
  int (*enable)(struct joybus *bus);
  int (*disable)(struct joybus *bus);
  int (*transfer)(struct joybus *bus, const uint8_t *write_buf, uint8_t write_len, uint8_t *read_buf, uint8_t read_len,
                  joybus_transfer_cb callback, void *user_data);
};
 
struct joybus_host_op {
  joybus_transfer_cb callback;
  void *user_data;
  uint8_t *response;
  uint8_t arg;
};

struct joybus {
  const struct joybus_api *api;

  enum joybus_mode mode;

  uint32_t freq;

  struct joybus_target *targets;

  struct joybus_target *active_target;
 
  uint8_t command_buffer[JOYBUS_BLOCK_SIZE];
  uint8_t response_buffer[JOYBUS_BLOCK_SIZE];
  struct joybus_host_op host_op;
};

static inline int joybus_enable(struct joybus *bus, enum joybus_mode mode)
{
  bus->mode = mode;
  return bus->api->enable(bus);
}

static inline int joybus_disable(struct joybus *bus)
{
  return bus->api->disable(bus);
}

static inline int joybus_transfer(struct joybus *bus, const uint8_t *write_buf, uint8_t write_len, uint8_t *read_buf,
                                  uint8_t read_len, joybus_transfer_cb callback, void *user_data)
{
  return bus->api->transfer(bus, write_buf, write_len, read_buf, read_len, callback, user_data);
}

int joybus_transfer_sync(struct joybus *bus, const uint8_t *write_buf, uint8_t write_len, uint8_t *read_buf,
                         uint8_t read_len);

int joybus_attach_target(struct joybus *bus, struct joybus_target *target);

int joybus_detach_target(struct joybus *bus, struct joybus_target *target);

static inline int joybus_byte_received(struct joybus *bus, const uint8_t *command, uint8_t byte_idx,
                                       joybus_target_response_cb send_response, void *user_data)
{
  // Later bytes go straight to the target that claimed the command
  if (byte_idx > 1)
    return joybus_target_byte_received(bus->active_target, command, byte_idx, send_response, user_data);
 
  // Offer the first byte to each target in attachment order until one claims the command
  for (struct joybus_target *target = bus->targets; target; target = target->next) {
    int rc = joybus_target_byte_received(target, command, byte_idx, send_response, user_data);
    if (rc == -JOYBUS_ERR_NOT_SUPPORTED)
      continue;
 
    bus->active_target = target;
    return rc;
  }
 
  // No target claimed the command
  bus->active_target = NULL;
  return -JOYBUS_ERR_NOT_SUPPORTED;
}
 
// Context for a blocking Joybus operation
struct joybus_sync_ctx {
  volatile bool done;
  volatile int status;
};
 
// Transfer completion callback that records the status into a joybus_sync_ctx.
void joybus_sync_cb(struct joybus *bus, int status, void *user_data);
 
// Busy-wait on a joybus_sync_ctx until the operation completes
int joybus_sync(int start_status, struct joybus_sync_ctx *ctx);