libgloss/arc/hl/hl_read.c

   1 /*
   2  * hl_read.c -- provide _read().
   3  *
   4  * Copyright (c) 2024 Synopsys Inc.
   5  *
   6  * The authors hereby grant permission to use, copy, modify, distribute,
   7  * and license this software and its documentation for any purpose, provided
   8  * that existing copyright notices are retained in all copies and that this
   9  * notice is included verbatim in any distributions. No written agreement,
  10  * license, or royalty fee is required for any of the authorized uses.
  11  * Modifications to this software may be copyrighted by their authors
  12  * and need not follow the licensing terms described here, provided that
  13  * the new terms are clearly indicated on the first page of each file where
  14  * they apply.
  15  *
  16  */
  17
  18 #include <errno.h>
  19 #include <stdint.h>
  20 #include <stddef.h>
  21 #include <unistd.h>
  22
  23 #include "hl_toolchain.h"
  24 #include "hl_api.h"
  25
  26
  27 /* Read one chunk.  Implements HL_SYSCALL_READ.  */
  28 static ssize_t
  29 _hl_read (int fd, void *buf, size_t count)
  30 {
  31   ssize_t ret;
  32   int32_t hl_n;
  33   uint32_t host_errno;
  34   volatile __uncached char *p;
  35
  36   p = _hl_message (HL_SYSCALL_READ, "ii:i",
  37                    (uint32_t) fd,      /* i */
  38                    (uint32_t) count,   /* i */
  39                    (uint32_t *) &hl_n  /* :i */);
  40
  41   if (p == NULL)
  42     {
  43       errno = ETIMEDOUT;
  44       ret = -1;
  45     }
  46   else if (hl_n < 0)
  47     {
  48       p = _hl_unpack_int (p, &host_errno);
  49       errno = p == NULL ? EIO : host_errno;
  50       ret = -1;
  51     }
  52   else
  53     {
  54       uint32_t n;
  55
  56       p = _hl_unpack_ptr (p, buf, &n);
  57       ret = n;
  58
  59       if (p == NULL || n != (uint32_t) hl_n)
  60         {
  61           errno = EIO;
  62           ret = -1;
  63         }
  64     }
  65
  66   _hl_delete ();
  67
  68   return ret;
  69 }
  70
  71 ssize_t
  72 _read (int fd, void *buf, size_t count)
  73 {
  74   const uint32_t hl_iochunk = _hl_iochunk_size ();
  75   size_t to_read = count;
  76   size_t offset = 0;
  77   ssize_t ret = 0;
  78
  79   while (to_read > hl_iochunk)
  80     {
  81       ret = _hl_read (fd, (char *) buf + offset, hl_iochunk);
  82
  83       if (ret < 0)
  84         return ret;
  85
  86       offset += ret;
  87
  88       if (ret != (ssize_t) hl_iochunk)
  89         return offset;
  90
  91       to_read -= hl_iochunk;
  92     }
  93
  94   if (to_read)
  95     {
  96       ret = _hl_read (fd, (char *) buf + offset, to_read);
  97
  98       if (ret < 0)
  99         return ret;
 100
 101       ret += offset;
 102     }
 103
 104   return ret;
 105 }