/*
 *                                                                                                  geany_encoding=koi8-r
 * flash.c
 *
 * Copyright 2017 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 *
 */

#include "stm32f1.h"

#include "flash.h"
#include "proto.h"
#include "usb.h"    // printout
#include <string.h> // memcpy

extern const uint32_t __varsstart, _BLOCKSIZE;
static const uint32_t FLASH_blocksize = (uint32_t)&_BLOCKSIZE;
static uint32_t maxCnum = 1024 / sizeof(user_conf); // can't use blocksize here

// common structure for all datatypes stored
/*typedef struct {
    uint16_t userconf_sz;
} flash_storage;*/

#define USERCONF_INITIALIZER  {         \
     .userconf_sz = sizeof(user_conf)   \
    ,.canspeed = 250                    \
    ,.canID = 0xAA                      \
    }

static int write2flash(const void*, const void*, uint32_t);
const user_conf *Flash_Data = (const user_conf *)(&__varsstart);
user_conf the_conf = USERCONF_INITIALIZER;

static int currentconfidx = -1; // index of current configuration

/**
 * @brief binarySearch - binary search in flash for last non-empty cell
 *          any struct searched should have its sizeof() @ the first field!!!
 * @param l - left index
 * @param r - right index (should be @1 less than last index!)
 * @param start - starting address
 * @param stor_size - size of structure to search
 * @return index of non-empty cell or -1
 */
static int binarySearch(int r, const uint8_t *start, int stor_size){
    int l = 0;
    while(r >= l){
        int mid = l + (r - l) / 2;
#ifdef EBUG
        USB_send("mid/l/r=");
        USB_send(u2str(mid)); USB_send("/");
        USB_send(u2str(l)); USB_send("/");
        USB_send(u2str(r)); USB_send("/");
        USB_send("\n");
#endif
        const uint8_t *s = start + mid * stor_size;
        if(*((const uint16_t*)s) == stor_size){
            if(*((const uint16_t*)(s + stor_size)) == 0xffff){ // next is free
                return mid;
            }else{ // element is to the right
                l = mid + 1;
            }
        }else{ // element is to the left
            r = mid - 1;
        }
    }
    return -1; // not found
}

/**
 * @brief flashstorage_init - initialization of user conf storage
 * run in once @ start
 */
void flashstorage_init(){
    if(FLASH_SIZE > 0 && FLASH_SIZE < 20000){
        uint32_t flsz = FLASH_SIZE * 1024; // size in bytes
        flsz -= (uint32_t)(&__varsstart) - FLASH_BASE;
        maxCnum = flsz / sizeof(user_conf);
    }
#ifdef EBUG
    USB_send("INIT\n");
#endif
    // -1 if there's no data at all & flash is clear; maxnum-1 if flash is full
    currentconfidx = binarySearch((int)maxCnum-2, (const uint8_t*)Flash_Data, sizeof(user_conf));
    if(currentconfidx > -1){
        memcpy(&the_conf, &Flash_Data[currentconfidx], sizeof(user_conf));
    }
#ifdef EBUG
    USB_send("currentconfidx="); USB_send(u2str(currentconfidx)); USB_send("\n");
#endif
}

// store new configuration
// @return 0 if all OK
int store_userconf(){
    // maxnum - 3 means that there always should be at least one empty record after last data
    // for binarySearch() checking that there's nothing more after it!
    if(currentconfidx > (int)maxCnum - 3){ // there's no more place
        currentconfidx = 0;
        if(erase_storage(-1)) return 1;
    }else ++currentconfidx; // take next data position (0 - within first run after firmware flashing)
    return write2flash((const void*)&Flash_Data[currentconfidx], &the_conf, sizeof(the_conf));
}

static int write2flash(const void *start, const void *wrdata, uint32_t stor_size){
    int ret = 0;
    if (FLASH->CR & FLASH_CR_LOCK){ // unloch flash
        FLASH->KEYR = FLASH_KEY1;
        FLASH->KEYR = FLASH_KEY2;
    }
    while (FLASH->SR & FLASH_SR_BSY)  IWDG->KR = IWDG_REFRESH;
    FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPRTERR; // clear all flags
    FLASH->CR |= FLASH_CR_PG;
    const uint16_t *data = (const uint16_t*) wrdata;
    volatile uint16_t *address = (volatile uint16_t*) start;
    uint32_t i, count = (stor_size + 1) / 2;
    for(i = 0; i < count; ++i){
        *(volatile uint16_t*)(address + i) = data[i];
        while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
        if(*(volatile uint16_t*)(address + i) != data[i]){
            USB_send("DON'T MATCH!\n");
            ret = 1;
            break;
        }
        if(FLASH->SR & FLASH_SR_PGERR){
            USB_send("Prog err\n");
            ret = 1; // program error - meet not 0xffff
            break;
        }
#ifdef EBUG
        USB_send(u2str(stor_size)); USB_send("bytes stored @0x");
        USB_send(u2hexstr((uint32_t)(address + i))); USB_send("\n");
#endif
        FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPRTERR;
    }
    FLASH->CR &= ~(FLASH_CR_PG);
    return ret;
}

// erase Nth page of flash storage (flash should be prepared!)
static int erase_pageN(int N){
    int ret = 0;
#ifdef EBUG
    USB_send("Erase page #"); USB_send(u2str(N)); USB_send("\n");
#endif
    FLASH->AR = (uint32_t)Flash_Data + N*FLASH_blocksize;
    FLASH->CR |= FLASH_CR_STRT;
    while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
    FLASH->SR = FLASH_SR_EOP;
    if(FLASH->SR & FLASH_SR_WRPRTERR){ /* Check Write protection error */
        ret = 1;
        FLASH->SR = FLASH_SR_WRPRTERR; /* Clear the flag by software by writing it at 1*/
    }
    return ret;
}

// erase full storage (npage < 0) or its nth page; @return 0 if all OK
int erase_storage(int npage){
    int ret = 0;
    uint32_t end = 1, start = 0, flsz = 0;
    if(FLASH_SIZE > 0 && FLASH_SIZE < 20000){
        flsz = FLASH_SIZE * 1024; // size in bytes
        flsz -= (uint32_t)Flash_Data - FLASH_BASE;
    }
    end = flsz / FLASH_blocksize;
#ifdef EBUG
    USB_send("FLASH_SIZE="); USB_send(u2str(FLASH_SIZE));
    USB_send("\nflsz="); USB_send(u2str(flsz));
    USB_send("\nend="); USB_send(u2str(end));
    USB_send("\ncurrentconfidx="); USB_send(u2str(currentconfidx));
    USB_send("\nmaxCnum="); USB_send(u2str(maxCnum));
    USB_send("\n");
#endif
    if(end == 0 || end >= FLASH_SIZE) return 1;
    if(npage > -1){ // erase only one page
        if((uint32_t)npage >= end) return 1;
        start = npage;
        end = start + 1;
    }
    if((FLASH->CR & FLASH_CR_LOCK) != 0){
        FLASH->KEYR = FLASH_KEY1;
        FLASH->KEYR = FLASH_KEY2;
    }
    while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
    FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPRTERR;
    FLASH->CR |= FLASH_CR_PER;
    for(uint32_t i = start; i < end; ++i){
        if(erase_pageN(i)){
            ret = 1;
            break;
        }
    }
    FLASH->CR &= ~FLASH_CR_PER;
    return ret;
}

void dump_userconf(){
    USB_send("userconf_sz="); printu(the_conf.userconf_sz);
    USB_send("\ncurrentconfidx="); USB_send(u2str(currentconfidx));
    USB_send("\nCAN_speed="); printu(the_conf.canspeed);
    USB_send("\nCAN_ID="); printu(the_conf.canID);
    USB_send("\nautoinit="); printu(the_conf.autoinit);
    USB_send("\n");
}