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libs/ck-libs/ampi/romio/adio/common/ad_read_str_naive.c

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/* -*- Mode: C; c-basic-offset:4 ; -*- */
/* 
 *
 *   Copyright (C) 2001 University of Chicago. 
 *   See COPYRIGHT notice in top-level directory.
 */

#include "adio.h"
#include "adio_extern.h"

void ADIOI_GEN_ReadStrided_naive(ADIO_File fd, void *buf, int count,
                       MPI_Datatype buftype, int file_ptr_type,
                       ADIO_Offset offset, ADIO_Status *status, int
                       *error_code)
{
    /* offset is in units of etype relative to the filetype. */

    ADIOI_Flatlist_node *flat_buf, *flat_file;
    ADIO_Offset size, brd_size, frd_size=0, req_len, sum;
    int b_index;
    int n_etypes_in_filetype;
    ADIO_Offset n_filetypes, etype_in_filetype;
    ADIO_Offset abs_off_in_filetype=0;
    unsigned bufsize, filetype_size, buftype_size, size_in_filetype;
    int etype_size;
    MPI_Aint filetype_extent, buftype_extent; 
    int buf_count, buftype_is_contig, filetype_is_contig;
    ADIO_Offset userbuf_off;
    ADIO_Offset off, req_off, disp, end_offset=0, start_off;
    ADIO_Status status1;

    *error_code = MPI_SUCCESS;  /* changed below if error */

    ADIOI_Datatype_iscontig(buftype, &buftype_is_contig);
    ADIOI_Datatype_iscontig(fd->filetype, &filetype_is_contig);

    MPI_Type_size(fd->filetype, (int*)&filetype_size);
    if ( ! filetype_size ) {
    *error_code = MPI_SUCCESS; 
    return;
    }

    MPI_Type_extent(fd->filetype, &filetype_extent);
    MPI_Type_size(buftype,(int*) &buftype_size);
    MPI_Type_extent(buftype, &buftype_extent);
    etype_size = fd->etype_size;

    ADIOI_Assert((buftype_size * count) == ((ADIO_Offset)buftype_size * (ADIO_Offset)count));
    bufsize = buftype_size * count;

    /* contiguous in buftype and filetype is handled elsewhere */

    if (!buftype_is_contig && filetype_is_contig) {
        int b_count;
    /* noncontiguous in memory, contiguous in file. */

    ADIOI_Flatten_datatype(buftype);
    flat_buf = CtvAccess(ADIOI_Flatlist);
    while (flat_buf->type != buftype) flat_buf = flat_buf->next;

        off = (file_ptr_type == ADIO_INDIVIDUAL) ? fd->fp_ind : 
              fd->disp + etype_size * offset;

    start_off = off;
    end_offset = off + bufsize - 1;

    /* if atomicity is true, lock (exclusive) the region to be accessed */
        if ((fd->atomicity) && ADIO_Feature(fd, ADIO_LOCKS))
    {
            ADIOI_WRITE_LOCK(fd, start_off, SEEK_SET, end_offset-start_off+1);
    }

    /* for each region in the buffer, grab the data and put it in
     * place
     */
        for (b_count=0; b_count < count; b_count++) {
            for (b_index=0; b_index < flat_buf->count; b_index++) {
                userbuf_off = (ADIO_Offset)b_count*(ADIO_Offset)buftype_extent + 
                      flat_buf->indices[b_index];
        req_off = off;
        req_len = flat_buf->blocklens[b_index];

    ADIOI_Assert((((ADIO_Offset)(MPIR_Upint)buf) + userbuf_off) == (ADIO_Offset)(MPIR_Upint)((MPIR_Upint)buf + userbuf_off));
    ADIOI_Assert(req_len == (int) req_len);
        ADIO_ReadContig(fd, 
                (char *) buf + userbuf_off,
                req_len, 
                MPI_BYTE, 
                    ADIO_EXPLICIT_OFFSET,
                req_off,
                &status1,
                error_code);
        if (*error_code != MPI_SUCCESS) return;

        /* off is (potentially) used to save the final offset later */
                off += flat_buf->blocklens[b_index];
            }
    }

        if ((fd->atomicity) && ADIO_Feature(fd, ADIO_LOCKS))
    {
            ADIOI_UNLOCK(fd, start_off, SEEK_SET, end_offset-start_off+1);
    }

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

    }

    else {  /* noncontiguous in file */
        int f_index, st_index = 0; 
      ADIO_Offset st_n_filetypes;
      ADIO_Offset st_frd_size;
    int flag;

        /* First we're going to calculate a set of values for use in all
     * the noncontiguous in file cases:
     * start_off - starting byte position of data in file
     * end_offset - last byte offset to be acessed in the file
     * st_n_filetypes - how far into the file we start in terms of
     *                  whole filetypes
     * st_index - index of block in first filetype that we will be
     *            starting in (?)
     * st_frd_size - size of the data in the first filetype block
     *               that we will read (accounts for being part-way
     *               into reading this block of the filetype
     *
     */

    /* filetype already flattened in ADIO_Open */
    flat_file = CtvAccess(ADIOI_Flatlist);
    while (flat_file->type != fd->filetype) flat_file = flat_file->next;
    disp = fd->disp;

    if (file_ptr_type == ADIO_INDIVIDUAL) {
        start_off = fd->fp_ind; /* in bytes */
        n_filetypes = -1;
        flag = 0;
        while (!flag) {
                n_filetypes++;
        for (f_index=0; f_index < flat_file->count; f_index++) {
            if (disp + flat_file->indices[f_index] + 
                       n_filetypes*(ADIO_Offset)filetype_extent + 
               flat_file->blocklens[f_index] >= start_off) 
            {
                /* this block contains our starting position */

            st_index = f_index;
            frd_size = disp + flat_file->indices[f_index] + 
                       n_filetypes*(ADIO_Offset)filetype_extent + 
                   flat_file->blocklens[f_index] - start_off;
            flag = 1;
            break;
            }
        }
        }
    }
    else {
        n_etypes_in_filetype = filetype_size/etype_size;
        n_filetypes = offset / n_etypes_in_filetype;
        etype_in_filetype = (int) (offset % n_etypes_in_filetype);
        size_in_filetype = (unsigned)etype_in_filetype * (unsigned)etype_size;
 
        sum = 0;
        for (f_index=0; f_index < flat_file->count; f_index++) {
        sum += flat_file->blocklens[f_index];
        if (sum > size_in_filetype) {
            st_index = f_index;
            frd_size = sum - size_in_filetype;
            abs_off_in_filetype = flat_file->indices[f_index] +
                              size_in_filetype - 
                              (sum - flat_file->blocklens[f_index]);
            break;
        }
        }

        /* abs. offset in bytes in the file */
        start_off = disp + n_filetypes*(ADIO_Offset)filetype_extent + 
                    abs_off_in_filetype;
    }

    st_frd_size = frd_size;
    st_n_filetypes = n_filetypes;

    /* start_off, st_n_filetypes, st_index, and st_frd_size are 
     * all calculated at this point
     */

        /* Calculate end_offset, the last byte-offset that will be accessed.
         * e.g., if start_off=0 and 100 bytes to be read, end_offset=99
     */
    userbuf_off = 0;
    f_index = st_index;
    off = start_off;
    frd_size = ADIOI_MIN(st_frd_size, bufsize);
    while (userbuf_off < bufsize) {
        userbuf_off += frd_size;
        end_offset = off + frd_size - 1;

        if (f_index < (flat_file->count - 1)) f_index++;
        else {
        f_index = 0;
        n_filetypes++;
        }

        off = disp + flat_file->indices[f_index] + 
              n_filetypes*(ADIO_Offset)filetype_extent;
        frd_size = ADIOI_MIN(flat_file->blocklens[f_index], 
                             bufsize-(unsigned)userbuf_off);
    }

    /* End of calculations.  At this point the following values have
     * been calculated and are ready for use:
     * - start_off
     * - end_offset
     * - st_n_filetypes
     * - st_index
     * - st_frd_size
     */

    /* if atomicity is true, lock (exclusive) the region to be accessed */
        if ((fd->atomicity) && ADIO_Feature(fd, ADIO_LOCKS))
    {
            ADIOI_WRITE_LOCK(fd, start_off, SEEK_SET, end_offset-start_off+1);
    }

    if (buftype_is_contig && !filetype_is_contig) {
        /* contiguous in memory, noncontiguous in file. should be the
         * most common case.
         */

        userbuf_off = 0;
        f_index = st_index;
        off = start_off;
        n_filetypes = st_n_filetypes;
        frd_size = ADIOI_MIN(st_frd_size, bufsize);

        /* while there is still space in the buffer, read more data */
        while (userbuf_off < bufsize) {
                if (frd_size) { 
                    /* TYPE_UB and TYPE_LB can result in 
                       frd_size = 0. save system call in such cases */ 
            req_off = off;
            req_len = frd_size;

        ADIOI_Assert((((ADIO_Offset)(MPIR_Upint)buf) + userbuf_off) == (ADIO_Offset)(MPIR_Upint)((MPIR_Upint)buf + userbuf_off));
        ADIOI_Assert(req_len == (int) req_len);
            ADIO_ReadContig(fd, 
                    (char *) buf + userbuf_off,
                    req_len, 
                    MPI_BYTE, 
                    ADIO_EXPLICIT_OFFSET,
                    req_off,
                    &status1,
                    error_code);
            if (*error_code != MPI_SUCCESS) return;
        }
        userbuf_off += frd_size;

                if (off + frd_size < disp + flat_file->indices[f_index] +
                   flat_file->blocklens[f_index] + 
           n_filetypes*(ADIO_Offset)filetype_extent)
        {
            /* important that this value be correct, as it is
             * used to set the offset in the fd near the end of
             * this function.
             */
                    off += frd_size;
        }
                /* did not reach end of contiguous block in filetype.
                 * no more I/O needed. off is incremented by frd_size.
         */
                else {
            if (f_index < (flat_file->count - 1)) f_index++;
            else {
            f_index = 0;
            n_filetypes++;
            }
            off = disp + flat_file->indices[f_index] + 
                          n_filetypes*(ADIO_Offset)filetype_extent;
            frd_size = ADIOI_MIN(flat_file->blocklens[f_index], 
                                 bufsize-(unsigned)userbuf_off);
        }
        }
    }
    else {
        ADIO_Offset i_offset, tmp_bufsize = 0;
        /* noncontiguous in memory as well as in file */

        ADIOI_Flatten_datatype(buftype);
        flat_buf = CtvAccess(ADIOI_Flatlist);
        while (flat_buf->type != buftype) flat_buf = flat_buf->next;

        b_index = buf_count = 0;
        i_offset = flat_buf->indices[0];
        f_index = st_index;
        off = start_off;
        n_filetypes = st_n_filetypes;
        frd_size = st_frd_size;
        brd_size = flat_buf->blocklens[0];

        /* while we haven't read size * count bytes, keep going */
        while (tmp_bufsize < bufsize) {
            ADIO_Offset new_brd_size = brd_size, new_frd_size = frd_size;

        size = ADIOI_MIN(frd_size, brd_size);
        if (size) {
            req_off = off;
            req_len = size;
            userbuf_off = i_offset;

        ADIOI_Assert((((ADIO_Offset)(MPIR_Upint)buf) + userbuf_off) == (ADIO_Offset)(MPIR_Upint)((MPIR_Upint)buf + userbuf_off));
        ADIOI_Assert(req_len == (int) req_len);
            ADIO_ReadContig(fd, 
                    (char *) buf + userbuf_off,
                    req_len, 
                    MPI_BYTE, 
                    ADIO_EXPLICIT_OFFSET,
                    req_off,
                    &status1,
                    error_code);
            if (*error_code != MPI_SUCCESS) return;
        }

        if (size == frd_size) {
            /* reached end of contiguous block in file */
            if (f_index < (flat_file->count - 1)) f_index++;
            else {
            f_index = 0;
            n_filetypes++;
            }

            off = disp + flat_file->indices[f_index] + 
                          n_filetypes*(ADIO_Offset)filetype_extent;

            new_frd_size = flat_file->blocklens[f_index];
            if (size != brd_size) {
            i_offset += size;
            new_brd_size -= size;
            }
        }

        if (size == brd_size) {
            /* reached end of contiguous block in memory */

            b_index = (b_index + 1)%flat_buf->count;
            buf_count++;
            i_offset = buftype_extent*(buf_count/flat_buf->count) +
            flat_buf->indices[b_index];
            new_brd_size = flat_buf->blocklens[b_index];
            if (size != frd_size) {
            off += size;
            new_frd_size -= size;
            }
        }
        tmp_bufsize += size;
        frd_size = new_frd_size;
                brd_size = new_brd_size;
        }
    }

    /* unlock the file region if we locked it */
        if ((fd->atomicity) && (fd->file_system != ADIO_PIOFS) && 
       (fd->file_system != ADIO_PVFS) && (fd->file_system != ADIO_PVFS2))
    {
            ADIOI_UNLOCK(fd, start_off, SEEK_SET, end_offset-start_off+1);
    }

    if (file_ptr_type == ADIO_INDIVIDUAL) fd->fp_ind = off;
    } /* end of (else noncontiguous in file) */

    fd->fp_sys_posn = -1;   /* mark it as invalid. */

#ifdef HAVE_STATUS_SET_BYTES
    MPIR_Status_set_bytes(status, buftype, bufsize);
    /* This is a temporary way of filling in status. The right way is to 
     * keep track of how much data was actually read and placed in buf 
     */
#endif

    if (!buftype_is_contig) ADIOI_Delete_flattened(buftype);
}

---