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libs/ck-libs/ampi/romio/adio/ad_xfs/ad_xfs_read.c

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/* -*- Mode: C; c-basic-offset:4 ; -*- */
/* 
 *
 *   Copyright (C) 1997 University of Chicago. 
 *   See COPYRIGHT notice in top-level directory.
 */

#include "ad_xfs.h"
#ifdef HAVE_MALLOC_H
#include <malloc.h>
#endif

/* style: allow:free:2 sig:0 */

static void ADIOI_XFS_Aligned_Mem_File_Read(ADIO_File fd, void *buf, int len, 
                         ADIO_Offset offset, int *err);

void ADIOI_XFS_ReadContig(ADIO_File fd, void *buf, int count, 
                     MPI_Datatype datatype, int file_ptr_type,
             ADIO_Offset offset, ADIO_Status *status, int *error_code)
{
    int err=-1, datatype_size, len, diff, size, nbytes;
    void *newbuf;
    static char myname[] = "ADIOI_XFS_READCONTIG";

    MPI_Type_size(datatype, &datatype_size);
    len = datatype_size * count;

    fd->fp_sys_posn = -1; /* set it to null, since we are using pread */

    if (file_ptr_type == ADIO_INDIVIDUAL) offset = fd->fp_ind;

    if (!(fd->direct_read))     /* direct I/O not enabled */
    err = pread(fd->fd_sys, buf, len, offset);
    else {       /* direct I/O enabled */

    /* (1) if mem_aligned && file_aligned 
                    use direct I/O to read up to correct io_size
                    use buffered I/O for remaining  */

    if (!(((long) buf) % fd->d_mem) && !(offset % fd->d_miniosz)) 
        ADIOI_XFS_Aligned_Mem_File_Read(fd, buf, len, offset, &err);

        /* (2) if !file_aligned
                    use buffered I/O to read up to file_aligned
                    At that point, if still mem_aligned, use (1)
                else copy into aligned buf and then use (1) */
    else if (offset % fd->d_miniosz) {
        diff = fd->d_miniosz - (offset % fd->d_miniosz);
        diff = ADIOI_MIN(diff, len);
        nbytes = pread(fd->fd_sys, buf, diff, offset);

        buf = ((char *) buf) + diff;
        offset += diff;
        size = len - diff;
        if (!(((long) buf) % fd->d_mem)) {
        ADIOI_XFS_Aligned_Mem_File_Read(fd, buf, size, offset, &err);
        nbytes += err;
        }
        else {
        newbuf = (void *) memalign(XFS_MEMALIGN, size);
        if (newbuf) {
            ADIOI_XFS_Aligned_Mem_File_Read(fd, newbuf, size, offset, &err);
            if (err > 0) memcpy(buf, newbuf, err);
            nbytes += err;
            ADIOI_Free(newbuf);
        }
        else nbytes += pread(fd->fd_sys, buf, size, offset);
        }
        err = nbytes;
    }

        /* (3) if !mem_aligned && file_aligned
                    copy into aligned buf, then use (1)  */
    else {
        newbuf = (void *) memalign(XFS_MEMALIGN, len);
        if (newbuf) {
        ADIOI_XFS_Aligned_Mem_File_Read(fd, newbuf, len, offset, &err);
        if (err > 0) memcpy(buf, newbuf, err);
        ADIOI_Free(newbuf);
        }
        else err = pread(fd->fd_sys, buf, len, offset);
    }
    }

    if (file_ptr_type == ADIO_INDIVIDUAL) fd->fp_ind += err;

#ifdef HAVE_STATUS_SET_BYTES
    if (err != -1) MPIR_Status_set_bytes(status, datatype, err);
#endif

    if (err == -1) {
    *error_code = MPIO_Err_create_code(MPI_SUCCESS, MPIR_ERR_RECOVERABLE,
                       myname, __LINE__, MPI_ERR_IO, "**io",
                       "**io %s", strerror(errno));
    }
    else *error_code = MPI_SUCCESS;
}


void ADIOI_XFS_Aligned_Mem_File_Read(ADIO_File fd, void *buf, int len, 
              ADIO_Offset offset, int *err)
{
    int ntimes, rem, newrem, i, size, nbytes;
    unsigned read_chunk_sz = fd->hints->fs_hints.xfs.read_chunk_sz;

    /* memory buffer is aligned, offset in file is aligned,
       io_size may or may not be of the right size.
       use direct I/O to read up to correct io_size,
       use buffered I/O for remaining. */

    if (!(len % fd->d_miniosz) && 
    (len >= fd->d_miniosz) && (len <= read_chunk_sz))
    *err = pread(fd->fd_direct, buf, len, offset);
    else if (len < fd->d_miniosz)
    *err = pread(fd->fd_sys, buf, len, offset);
    else if (len > read_chunk_sz) {
    ntimes = len/(read_chunk_sz);
    rem = len - ntimes * read_chunk_sz;
    nbytes = 0;
    for (i=0; i<ntimes; i++) {
        nbytes += pread(fd->fd_direct, ((char *)buf) + i * read_chunk_sz,
             read_chunk_sz, offset);
        offset += read_chunk_sz;
    }
    if (rem) {
        if (!(rem % fd->d_miniosz))
        nbytes += pread(fd->fd_direct, 
             ((char *)buf) + ntimes * read_chunk_sz, rem, offset);
        else {
        newrem = rem % fd->d_miniosz;
        size = rem - newrem;
        if (size) {
            nbytes += pread(fd->fd_direct, 
                 ((char *)buf) + ntimes * read_chunk_sz, size, offset);
            offset += size;
        }
        nbytes += pread(fd->fd_sys, 
                  ((char *)buf) + ntimes * read_chunk_sz + size, newrem, offset);
        }
    }
    *err = nbytes;
    }
    else {
    rem = len % fd->d_miniosz;
    size = len - rem;
    nbytes = pread(fd->fd_direct, buf, size, offset);
    nbytes += pread(fd->fd_sys, (char *)buf + size, rem, offset+size);
    *err = nbytes;
    }
}

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