c - 使用 FatFs 会导致 PIC18F46J50 uC 上的 f_write 无限循环

Question

几天来，我一直在尝试为一个项目实现 FatFs 模块。我的低级 I/O 配置已正确实现，因为我可以使用示波器查看信号。但我似乎无法在 SD 卡 上进行正确的写入。我得到的只是我的 SD-Card 上的一个空文件，该文件已正确创建。读取文件也能正常工作。当我使用 MPLAB X 进行调试时，我发现 f_write 函数永远不会离开 for 循环。

这是我的 main.c 代码:

/*
Main application
*/

 FATFS FatFs;
 FIL fil1, fil2;

void main(void)
{
            SYSTEM_Init();

            BYTE buffer[4];
            UINT bw, br;
            FRESULT fr;

            if(f_mount(&FatFs, "", 1) == FR_OK)
            {
                    //open source file
                   fr = f_open(&fil1, "READ.TXT", FA_READ); 
                   if(fr) return; 

                   //create destination file
                   fr = f_open(&fil2, "WRITE.TXT", FA_WRITE | FA_CREATE_ALWAYS);
                   if(fr) return;

                   //copy 1 to 2

                   for(;;){

                       fr = f_read(&fil1, buffer, sizeof buffer, &br);
                       if(fr || br == 0) break;

                       fr = f_write(&fil2, buffer, br, &bw);
                       if(fr || bw < br) break;

                   }
//                      const char *writedata = &write;
//                       //f_printf(&fil, "%d", 1234);
//                       f_write(&fil, writedata, strlen(writedata), &bw);

                       f_close(&fil1);
                       f_close(&fil2);

                       f_mount(NULL, "", 0);

                   }

    return;
}

这是我的 diskio.c 代码:

/*-----------------------------------------------------------------------*/
/* Low level disk I/O module skeleton for FatFs     (C)ChaN, 2016        */
/*-----------------------------------------------------------------------*/
/* If a working storage control module is available, it should be        */
/* attached to the FatFs via a glue function rather than modifying it.   */
/* This is an example of glue functions to attach various exsisting      */
/* storage control modules to the FatFs module with a defined API.       */
/*-----------------------------------------------------------------------*/

#ifdef __XC8
#include <p18f46j50.h>
#endif

#ifndef __XC8
#include <p18cxxx.h>
#endif

#include "diskio.h" /* FatFs lower layer API */
#include "sdspi.h"
#include "sdctrl.h"

/* Definitions of physical drive number for each drive */
#define DEV_RAM     0   /* Example: Map Ramdisk to physical drive 0 */
#define DEV_MMC     1   /* Example: Map MMC/SD card to physical drive 1 */
#define DEV_USB     2   /* Example: Map USB MSD to physical drive 2 */

#define _XTAL_FREQ 8000000


/*--------------------------------------------------------------------------

   Module Private Functions

---------------------------------------------------------------------------*/

/* Definitions for SDC command */
#define CMD0    (0)         /* GO_IDLE_STATE */
#define CMD1    (1)         /* SEND_OP_COND (MMC) */
#define ACMD41  (0x80+41)   /* SEND_OP_COND (SDC) */
#define CMD8    (8)         /* SEND_IF_COND */
#define CMD9    (9)         /* SEND_CSD */
#define CMD10   (10)        /* SEND_CID */
#define CMD12   (12)        /* STOP_TRANSMISSION */
#define ACMD13  (0x80+13)   /* SD_STATUS (SDC) */
#define CMD16   (16)        /* SET_BLOCKLEN */
#define CMD17   (17)        /* READ_SINGLE_BLOCK */
#define CMD18   (18)        /* READ_MULTIPLE_BLOCK */
#define CMD23   (23)        /* SET_BLOCK_COUNT (MMC) */
#define ACMD23  (0x80+23)   /* SET_WR_BLK_ERASE_COUNT (SDC) */
#define CMD24   (24)        /* WRITE_BLOCK */
#define CMD25   (25)        /* WRITE_MULTIPLE_BLOCK */
#define CMD32   (32)        /* ERASE_ER_BLK_START */
#define CMD33   (33)        /* ERASE_ER_BLK_END */
#define CMD38   (38)        /* ERASE */
#define CMD55   (55)        /* APP_CMD */
#define CMD58   (58)        /* READ_OCR */


/* MMC card type flags (MMC_GET_TYPE) */
#define CT_MMC      0x01        /* MMC ver 3 */
#define CT_SD1      0x02        /* SD ver 1 */
#define CT_SD2      0x04        /* SD ver 2 */
#define CT_SDC      (CT_SD1|CT_SD2) /* SD */
#define CT_BLOCK    0x08        /* Block addressing */


static
DSTATUS Stat = STA_NOINIT;  /* Disk status */

static
BYTE CardType;          /* Card type flags */



/*-----------------------------------------------------------------------*/
/* Wait for card ready                                                   */
/*-----------------------------------------------------------------------*/

static
BYTE wait_ready (void)  /* 1:Ready, 0:Timeout */
{
    UINT tmr;


    for (tmr = 5000; tmr; tmr--) {  /* Wait for ready in timeout of 500ms */
        if (sdspi_rxByte() == 0xFF) break;
        __delay_us(100);
    }

    return tmr ? 1 : 0;
}



/*-----------------------------------------------------------------------*/
/* Deselect the card and release SPI bus                                 */
/*-----------------------------------------------------------------------*/

static
void deselect (void)
{
    sd_deselect();  /* Set CS# high */
    sdspi_rxByte(); /* Dummy clock (force DO hi-z for multiple slave SPI) */
}



/*-----------------------------------------------------------------------*/
/* Select the card and wait for ready                                    */
/*-----------------------------------------------------------------------*/

static
BYTE select (void)  /* 1:Successful, 0:Timeout */
{
    sd_select();    /* Set CS# low */
    sdspi_rxByte(); /* Dummy clock (force DO enabled) */
    if (wait_ready()) return 1; /* Wait for card ready */

    deselect();
    return 0;   /* Timeout */
}



/*-----------------------------------------------------------------------*/
/* Receive a data packet from MMC                                        */
/*-----------------------------------------------------------------------*/

static
BYTE rcvr_datablock (
    BYTE *buff,         /* Data buffer to store received data */
    UINT btr            /* Byte count (must be multiple of 4) */
)
{
    BYTE token;
    UINT tmr;


    for (tmr = 2000; tmr; tmr--) {  /* Wait for data packet in timeout of 200ms */
        token = sdspi_rxByte();
        if (token != 0xFF) break;
//      __delay_us(100);
    }
    if (token != 0xFE) return 0;    /* If not valid data token, retutn with error */

    do
        *buff++ = sdspi_rxByte();       /* Receive the data block into buffer */
    while (--btr);
    sdspi_rxByte();                 /* Discard CRC */
    sdspi_rxByte();

    return 1;                   /* Return with success */
}



/*-----------------------------------------------------------------------*/
/* Send a data packet to MMC                                             */
/*-----------------------------------------------------------------------*/

#if _USE_WRITE
static
BYTE xmit_datablock (
    const BYTE *buff,   /* 512 byte data block to be transmitted */
    BYTE token          /* Data/Stop token */
)
{
    BYTE resp;
    WORD i;


    if (!wait_ready()) return 0;

    sdspi_txByte(token);            /* Xmit data token */
    if (token != 0xFD) {    /* Is data token */
        i = 512;
        do
        {
            sdspi_txByte(*buff++);              /* Xmit the data block to the MMC */
            __delay_us(100);
        }while (--i);


        sdspi_rxByte();                     /* CRC (Dummy) */
        sdspi_rxByte();

        resp = sdspi_rxByte();                  /* Reveive data response */
        if ((resp & 0x1F) != 0x05)      /* If not accepted, return with error */
            return 0;
    }

    return 1;
}
#endif



/*-----------------------------------------------------------------------*/
/* Send a command packet to MMC                                          */
/*-----------------------------------------------------------------------*/

/* NOTE: XC8 compiler is unable to allow recursion,
/  so the send_cmd function had to be divided */

#ifdef __XC8
static
BYTE __send_cmd (       /* Returns R1 resp (bit7==1:Send failed) */
    BYTE cmd,       /* Command index */
    DWORD arg       /* Argument */
)
{
    BYTE n, res;


    /* Select the card and wait for ready except to stop multiple block read */
    if (cmd != CMD12) {
        sd_deselect();
        if (!select()) return 0xFF;
//      sd_select();
//        if (wait_ready() != 0xFF) return 0xFF;
    }

    /* Send command packet */
    sdspi_txByte(0x40 | cmd);               /* Start + Command index */
    sdspi_txByte((BYTE)(arg >> 24));        /* Argument[31..24] */
    sdspi_txByte((BYTE)(arg >> 16));        /* Argument[23..16] */
    sdspi_txByte((BYTE)(arg >> 8));     /* Argument[15..8] */
    sdspi_txByte((BYTE)arg);                /* Argument[7..0] */
    n = 0x01;                       /* Dummy CRC + Stop */
    if (cmd == CMD0) n = 0x95;      /* Valid CRC for CMD0(0) + Stop */
    if (cmd == CMD8) n = 0x87;      /* Valid CRC for CMD8(0x1AA) Stop */
    sdspi_txByte(n);

    /* Receive command response */
    if (cmd == CMD12) sdspi_rxByte();       /* Skip a stuff byte when stop reading */
    n = 10;                             /* Wait for a valid response in timeout of 10 attempts */
    do
        res = sdspi_rxByte();
    while ((res & 0x80) && --n);

    return res;         /* Return with the response value */
}
#endif

static
BYTE send_cmd (     /* Returns R1 resp (bit7==1:Send failed) */
    BYTE cmd,       /* Command index */
    DWORD arg       /* Argument */
)
{
#ifndef __XC8
    BYTE n;
#endif
    BYTE res;


    if (cmd & 0x80) {   /* ACMD<n> is the command sequense of CMD55-CMD<n> */
        cmd &= 0x7F;
#ifdef __XC8
        res = __send_cmd(CMD55, 0);
#else
        res = send_cmd(CMD55, 0);
#endif
        if (res > 1) return res;
    }

#ifdef __XC8
    return __send_cmd(cmd, arg);    /* Return with the response value */
#else
    /* Select the card and wait for ready except to stop multiple block read */
    if (cmd != CMD12) {
        sd_deselect();
        if (!select()) return 0xFF;
    }

    /* Send command packet */
    sdspi_txByte(0x40 | cmd);               /* Start + Command index */
    sdspi_txByte((BYTE)(arg >> 24));        /* Argument[31..24] */
    sdspi_txByte((BYTE)(arg >> 16));        /* Argument[23..16] */
    sdspi_txByte((BYTE)(arg >> 8));     /* Argument[15..8] */
    sdspi_txByte((BYTE)arg);                /* Argument[7..0] */
    n = 0x01;                       /* Dummy CRC + Stop */
    if (cmd == CMD0) n = 0x95;      /* Valid CRC for CMD0(0) + Stop */
    if (cmd == CMD8) n = 0x87;      /* Valid CRC for CMD8(0x1AA) Stop */
    sdspi_txByte(n);

    /* Receive command response */
    if (cmd == CMD12) sdspi_rxByte();       /* Skip a stuff byte when stop reading */
    n = 10;                             /* Wait for a valid response in timeout of 10 attempts */
    do
        res = sdspi_rxByte();
    while ((res & 0x80) && --n);

    return res;         /* Return with the response value */
#endif
}



/*--------------------------------------------------------------------------

   Public Functions

---------------------------------------------------------------------------*/


/*-----------------------------------------------------------------------*/
/* Initialize Disk Drive                                                 */
/*-----------------------------------------------------------------------*/

DSTATUS disk_initialize (
    BYTE pdrv       /* Physical drive nmuber (0) */
)
{
    BYTE n, cmd, ty, ocr[4];
    UINT tmr;


    if (pdrv) return STA_NOINIT;        /* Supports only single drive */

    if (Stat & STA_NODISK) return Stat; /* No card in the socket */

    sdspi_enable();                         /* Enable the SPI port */
    sdspi_setSlowMode();                    /* Setup for slow mode */
    for (n = 10; n; n--) sdspi_rxByte();    /* 80 dummy clocks */

    ty = 0;
    if (send_cmd(CMD0, 0) == 1) {           /* Enter Idle state */
        if (send_cmd(CMD8, 0x1AA) == 1) {   /* SDv2? */
            for (n = 0; n < 4; n++) ocr[n] = sdspi_rxByte();    /* Get trailing return value of R7 resp */
            if (ocr[2] == 0x01 && ocr[3] == 0xAA) {     /* The card can work at vdd range of 2.7-3.6V */
                for (tmr = 1000; tmr; tmr--) {          /* Wait for leaving idle state (ACMD41 with HCS bit) */
                    if (send_cmd(ACMD41, 1UL << 30) == 0) break;
                    __delay_ms(1);
                }
                if (tmr && send_cmd(CMD58, 0) == 0) {       /* Check CCS bit in the OCR */
                    for (n = 0; n < 4; n++) ocr[n] = sdspi_rxByte();
                    ty = (ocr[0] & 0x40) ? CT_SD2 | CT_BLOCK : CT_SD2;  /* SDv2 */
                }
            }
        } else {                            /* SDv1 or MMCv3 */
            if (send_cmd(ACMD41, 0) <= 1)   {
                ty = CT_SD1; cmd = ACMD41;  /* SDv1 */
            } else {
                ty = CT_MMC; cmd = CMD1;    /* MMCv3 */
            }
            for (tmr = 1000; tmr; tmr--) {          /* Wait for leaving idle state */
                if (send_cmd(cmd, 0) == 0) break;
                __delay_ms(1);
            }
            if (!tmr || send_cmd(CMD16, 512) != 0)  /* Set R/W block length to 512 */
                ty = 0;
        }
    }
    CardType = ty;
    deselect();

    if (ty) {           /* Initialization succeded */
        Stat &= ~STA_NOINIT;        /* Clear STA_NOINIT */
        sdspi_setFastMode();
    }

    return Stat;
}



/*-----------------------------------------------------------------------*/
/* Get Disk Status                                                       */
/*-----------------------------------------------------------------------*/

DSTATUS disk_status (
    BYTE pdrv       /* Physical drive nmuber (0) */
)
{
    if (pdrv) return STA_NOINIT;    /* Supports only single drive */
    return Stat;
}



/*-----------------------------------------------------------------------*/
/* Read Sector(s)                                                        */
/*-----------------------------------------------------------------------*/

DRESULT disk_read (
    BYTE pdrv,          /* Physical drive nmuber (0) */
    BYTE *buff,         /* Pointer to the data buffer to store read data */
    DWORD sector,       /* Start sector number (LBA) */
    UINT count          /* Sector count (1..128) */
)
{
    BYTE cmd;


    if (pdrv || !count) return RES_PARERR;
    if (Stat & STA_NOINIT) return RES_NOTRDY;

    if (!(CardType & CT_BLOCK)) sector *= 512;  /* Convert to byte address if needed */

    cmd = count > 1 ? CMD18 : CMD17;            /*  READ_MULTIPLE_BLOCK : READ_SINGLE_BLOCK */
    if (send_cmd(cmd, sector) == 0) {
        do {
            if (!rcvr_datablock(buff, 512)) break;
            buff += 512;
        } while (--count);
        if (cmd == CMD18) send_cmd(CMD12, 0);   /* STOP_TRANSMISSION */
    }
    deselect();

    return count ? RES_ERROR : RES_OK;
}



/*-----------------------------------------------------------------------*/
/* Write Sector(s)                                                       */
/*-----------------------------------------------------------------------*/

#if _USE_WRITE
DRESULT disk_write (
    BYTE pdrv,          /* Physical drive nmuber (0) */
    const BYTE *buff,   /* Pointer to the data to be written */
    DWORD sector,       /* Start sector number (LBA) */
    UINT count          /* Sector count (1..128) */
)
{
    if (pdrv || !count) return RES_PARERR;
    if (Stat & STA_NOINIT) return RES_NOTRDY;
    if (Stat & STA_PROTECT) return RES_WRPRT;

    if (!(CardType & CT_BLOCK)) sector *= 512;  /* Convert to byte address if needed */

    if (count == 1) {   /* Single block write */
        if ((send_cmd(CMD24, sector) == 0)  /* WRITE_BLOCK */
            && xmit_datablock(buff, 0xFE))
            count = 0;
    }
    else {              /* Multiple block write */
        if (CardType & CT_SDC) send_cmd(ACMD23, count);
        if (send_cmd(CMD25, sector) == 0) { /* WRITE_MULTIPLE_BLOCK */
            do {
                if (!xmit_datablock(buff, 0xFC)) break;
                buff += 512;
            } while (--count);
            if (!xmit_datablock(0, 0xFD))   /* STOP_TRAN token */
                count = 1;
        }
    }
    deselect();

    return count ? RES_ERROR : RES_OK;
}
#endif


/*-----------------------------------------------------------------------*/
/* Miscellaneous Functions                                               */
/*-----------------------------------------------------------------------*/

//#if _USE_IOCTL
DRESULT disk_ioctl (
    BYTE pdrv,      /* Physical drive nmuber (0) */
    BYTE cmd,       /* Control code */
    void *buff      /* Buffer to send/receive control data */
)
{
    DRESULT res;
    BYTE n, csd[16], *ptr = buff;
    DWORD csize;


    if (pdrv) return RES_PARERR;

    res = RES_ERROR;

    if (Stat & STA_NOINIT) return RES_NOTRDY;

    switch (cmd) {
    case CTRL_SYNC :        /* Make sure that no pending write process. Do not remove this or written sector might not left updated. */
        if (select()) res = RES_OK;
        break;

    case GET_SECTOR_COUNT : /* Get number of sectors on the disk (DWORD) */
        if ((send_cmd(CMD9, 0) == 0) && rcvr_datablock(csd, 16)) {
            if ((csd[0] >> 6) == 1) {   /* SDC ver 2.00 */
                csize = csd[9] + ((WORD)csd[8] << 8) + ((DWORD)(csd[7] & 63) << 16) + 1;
                *(DWORD*)buff = csize << 10;
            } else {                    /* SDC ver 1.XX or MMC*/
                n = (csd[5] & 15) + ((csd[10] & 128) >> 7) + ((csd[9] & 3) << 1) + 2;
                csize = (csd[8] >> 6) + ((WORD)csd[7] << 2) + ((WORD)(csd[6] & 3) << 10) + 1;
                *(DWORD*)buff = csize << (n - 9);
            }
            res = RES_OK;
        }
        break;

    case GET_BLOCK_SIZE :   /* Get erase block size in unit of sector (DWORD) */
        if (CardType & CT_SD2) {    /* SDv2? */
            if (send_cmd(ACMD13, 0) == 0) { /* Read SD status */
                sdspi_rxByte();
                if (rcvr_datablock(csd, 16)) {              /* Read partial block */
                    for (n = 64 - 16; n; n--) sdspi_rxByte();   /* Purge trailing data */
                    *(DWORD*)buff = 16UL << (csd[10] >> 4);
                    res = RES_OK;
                }
            }
        } else {                    /* SDv1 or MMCv3 */
            if ((send_cmd(CMD9, 0) == 0) && rcvr_datablock(csd, 16)) {  /* Read CSD */
                if (CardType & CT_SD1) {    /* SDv1 */
                    *(DWORD*)buff = (((csd[10] & 63) << 1) + ((WORD)(csd[11] & 128) >> 7) + 1) << ((csd[13] >> 6) - 1);
                } else {                    /* MMCv3 */
                    *(DWORD*)buff = ((WORD)((csd[10] & 124) >> 2) + 1) * (((csd[11] & 3) << 3) + ((csd[11] & 224) >> 5) + 1);
                }
                res = RES_OK;
            }
        }
        break;

    /* Following commands are never used by FatFs module */

    case MMC_GET_TYPE :     /* Get card type flags (1 byte) */
        *ptr = CardType;
        res = RES_OK;
        break;

    case MMC_GET_CSD :      /* Receive CSD as a data block (16 bytes) */
        if (send_cmd(CMD9, 0) == 0      /* READ_CSD */
            && rcvr_datablock(ptr, 16))
            res = RES_OK;
        break;

    case MMC_GET_CID :      /* Receive CID as a data block (16 bytes) */
        if (send_cmd(CMD10, 0) == 0     /* READ_CID */
            && rcvr_datablock(ptr, 16))
            res = RES_OK;
        break;

    case MMC_GET_OCR :      /* Receive OCR as an R3 resp (4 bytes) */
        if (send_cmd(CMD58, 0) == 0) {  /* READ_OCR */
            for (n = 4; n; n--) *ptr++ = sdspi_rxByte();
            res = RES_OK;
        }
        break;

    case MMC_GET_SDSTAT :   /* Receive SD statsu as a data block (64 bytes) */
        if (send_cmd(ACMD13, 0) == 0) { /* SD_STATUS */
            sdspi_rxByte();
            if (rcvr_datablock(ptr, 64))
                res = RES_OK;
        }
        break;

    default:
        res = RES_PARERR;
    }

    deselect();

    return res;
}
//#endif

这是 ff.c

中的 f_write() 函数

FRESULT f_write (
    FIL* fp,            /* Pointer to the file object */
    const void* buff,   /* Pointer to the data to be written */
    UINT btw,           /* Number of bytes to write */
    UINT* bw            /* Pointer to number of bytes written */
)
{
    FRESULT res;
    FATFS *fs;
    DWORD clst, sect;
    UINT wcnt, cc, csect;
    const BYTE *wbuff = (const BYTE*)buff;


    *bw = 0;    /* Clear write byte counter */
    res = validate(&fp->obj, &fs);          /* Check validity of the file object */
    if (res != FR_OK || (res = (FRESULT)fp->err) != FR_OK) LEAVE_FF(fs, res);   /* Check validity */
    if (!(fp->flag & FA_WRITE)) LEAVE_FF(fs, FR_DENIED);    /* Check access mode */

    /* Check fptr wrap-around (file size cannot reach 4GiB on FATxx) */
    if ((!_FS_EXFAT || fs->fs_type != FS_EXFAT) && (DWORD)(fp->fptr + btw) < (DWORD)fp->fptr) {
        btw = (UINT)(0xFFFFFFFF - (DWORD)fp->fptr);
    }



// HERE DOES THE LOOP HAPPEN

    for ( ;  btw;                           /* Repeat until all data written */
        wbuff += wcnt, fp->fptr += wcnt, fp->obj.objsize = (fp->fptr > fp->obj.objsize) ? fp->fptr : fp->obj.objsize, *bw += wcnt, btw -= wcnt) {
        if (fp->fptr % SS(fs) == 0) {       /* On the sector boundary? */
            csect = (UINT)(fp->fptr / SS(fs)) & (fs->csize - 1);    /* Sector offset in the cluster */
            if (csect == 0) {               /* On the cluster boundary? */
                if (fp->fptr == 0) {        /* On the top of the file? */
                    clst = fp->obj.sclust;  /* Follow from the origin */
                    if (clst == 0) {        /* If no cluster is allocated, */
                        clst = create_chain(&fp->obj, 0);   /* create a new cluster chain */
                    }
                } else {                    /* On the middle or end of the file */
#if _USE_FASTSEEK
                    if (fp->cltbl) {
                        clst = clmt_clust(fp, fp->fptr);    /* Get cluster# from the CLMT */
                    } else
#endif
                    {
                        clst = create_chain(&fp->obj, fp->clust);   /* Follow or stretch cluster chain on the FAT */
                    }
                }
                if (clst == 0) break;       /* Could not allocate a new cluster (disk full) */
                if (clst == 1) ABORT(fs, FR_INT_ERR);
                if (clst == 0xFFFFFFFF) ABORT(fs, FR_DISK_ERR);
                fp->clust = clst;           /* Update current cluster */
                if (fp->obj.sclust == 0) fp->obj.sclust = clst; /* Set start cluster if the first write */
            }
#if _FS_TINY
            if (fs->winsect == fp->sect && sync_window(fs) != FR_OK) ABORT(fs, FR_DISK_ERR);    /* Write-back sector cache */
#else
            if (fp->flag & FA_DIRTY) {      /* Write-back sector cache */
                if (disk_write(fs->drv, fp->buf, fp->sect, 1) != RES_OK) ABORT(fs, FR_DISK_ERR);
                fp->flag &= (BYTE)~FA_DIRTY;
            }
#endif
            sect = clust2sect(fs, fp->clust);   /* Get current sector */
            if (!sect) ABORT(fs, FR_INT_ERR);
            sect += csect;
            cc = btw / SS(fs);              /* When remaining bytes >= sector size, */
            if (cc) {                       /* Write maximum contiguous sectors directly */
                if (csect + cc > fs->csize) {   /* Clip at cluster boundary */
                    cc = fs->csize - csect;
                }
                if (disk_write(fs->drv, wbuff, sect, cc) != RES_OK) ABORT(fs, FR_DISK_ERR);
#if _FS_MINIMIZE <= 2
#if _FS_TINY
                if (fs->winsect - sect < cc) {  /* Refill sector cache if it gets invalidated by the direct write */
                    mem_cpy(fs->win, wbuff + ((fs->winsect - sect) * SS(fs)), SS(fs));
                    fs->wflag = 0;
                }
#else
                if (fp->sect - sect < cc) { /* Refill sector cache if it gets invalidated by the direct write */
                    mem_cpy(fp->buf, wbuff + ((fp->sect - sect) * SS(fs)), SS(fs));
                    fp->flag &= (BYTE)~FA_DIRTY;
                }
#endif
#endif
                wcnt = SS(fs) * cc;     /* Number of bytes transferred */
                continue;
            }
#if _FS_TINY
            if (fp->fptr >= fp->obj.objsize) {  /* Avoid silly cache filling on the growing edge */
                if (sync_window(fs) != FR_OK) ABORT(fs, FR_DISK_ERR);
                fs->winsect = sect;
            }
#else
            if (fp->sect != sect &&         /* Fill sector cache with file data */
                fp->fptr < fp->obj.objsize &&
                disk_read(fs->drv, fp->buf, sect, 1) != RES_OK) {
                    ABORT(fs, FR_DISK_ERR);
            }
#endif
            fp->sect = sect;
        }
        wcnt = SS(fs) - (UINT)fp->fptr % SS(fs);    /* Number of bytes left in the sector */
        if (wcnt > btw) wcnt = btw;                 /* Clip it by btw if needed */
#if _FS_TINY
        if (move_window(fs, fp->sect) != FR_OK) ABORT(fs, FR_DISK_ERR); /* Move sector window */
        mem_cpy(fs->win + fp->fptr % SS(fs), wbuff, wcnt);  /* Fit data to the sector */
        fs->wflag = 1;
#else
        mem_cpy(fp->buf + fp->fptr % SS(fs), wbuff, wcnt);  /* Fit data to the sector */
        fp->flag |= FA_DIRTY;
#endif
    }

    fp->flag |= FA_MODIFIED;                /* Set file change flag */

    LEAVE_FF(fs, FR_OK);
}

Answer 1

信不信由你，我遇到了完全相同的问题并为此纠结了几个小时...这与 XC8 编译器解释 for 循环迭代器表达式的方式有关。看起来它要执行的表达式数量有一个硬性限制。如果编译器至少发出警告就好了……要修复它，请添加

    fp->fptr += wcnt;
    fp->obj.objsize = (fp->fptr > fp->obj.objsize) ? fp->fptr : fp->obj.objsize;
    *bw += wcnt;
    btw -= wcnt;

到for循环的底部，将for循环改为

    for ( ;  btw; wbuff += wcnt){//, fp->fptr += wcnt, fp->obj.objsize = (fp->fptr > fp->obj.objsize) ? fp->fptr : fp->obj.objsize, *bw += wcnt, btw -= wcnt) {