#ifndef PID_FLASH_H
#define PID_FLASH_H

#include <stdint.h>
#include <stdbool.h>

/*
 * pid_flash — persistent PID storage for Issue #531 (auto-tune).
 *
 * Stores Kp, Ki, Kd in the last 64 bytes of STM32F722 flash sector 7
 * (0x0807FFC0). Magic word validates presence of saved params.
 * Sector 7 is 128KB starting at 0x08060000; firmware never exceeds sector 6.
 *
 * Flash writes require an erase of the full sector (128KB) before re-writing.
 * The store address is the very last 64-byte block so future expansion can
 * grow toward lower addresses within sector 7 without conflict.
 */

#define PID_FLASH_SECTOR        FLASH_SECTOR_7
#define PID_FLASH_SECTOR_VOLTAGE VOLTAGE_RANGE_3   /* 2.7V-3.6V, 32-bit parallelism */

/* Sector 7: 128KB at 0x08060000; store in last 64 bytes */
#define PID_FLASH_STORE_ADDR    0x0807FFC0UL
#define PID_FLASH_MAGIC         0x534C5401UL   /* 'SLT\x01' — version 1 */

typedef struct __attribute__((packed)) {
    uint32_t magic;       /* PID_FLASH_MAGIC when valid */
    float    kp;
    float    ki;
    float    kd;
    uint8_t  _pad[48];   /* padding to 64 bytes */
} pid_flash_t;

/*
 * pid_flash_load() — read saved PID from flash.
 * Returns true and fills *kp/*ki/*kd if magic is valid.
 * Returns false if no valid params stored (caller keeps defaults).
 */
bool pid_flash_load(float *kp, float *ki, float *kd);

/*
 * pid_flash_save() — erase sector 7 and write Kp/Ki/Kd.
 * Must not be called while armed (flash erase takes ~1s and stalls the CPU).
 * Returns true on success.
 */
bool pid_flash_save(float kp, float ki, float kd);

#endif /* PID_FLASH_H */