Changeset 20667af in mainline for uspace/lib/riff/src/chunk.c

Timestamp:

2020-11-21T19:56:45Z (3 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

68698ba

Parents:

06d0c81

git-author:

Jiri Svoboda <jiri@…> (2020-11-21 19:25:27)

git-committer:

Jiri Svoboda <jiri@…> (2020-11-21 19:56:45)

Message:

Remember current position in libriff and optimize sequential reading

TPF files currently contain a lot of chunks and each chunk means
a ftell/fseek. libc's ftell/fseek flush the I/O buffer, leading
to a lot of unnecessary IPC. This all leads to reading typeface to
take way too long.

We remember the current file position
in a RIFF reader and avoid ftell and also avoid fseek at the end
of a chunk, if possible (if we need to advance just a little bit,
we read instead of seek).

File:

• uspace/lib/riff/src/chunk.c (modified) (8 diffs)

uspace/lib/riff/src/chunk.c

@@ -213 +213 @@
         }
 
+        rr->pos = 0;
+
         rr->f = fopen(fname, "rb");
         if (rr->f == NULL) {
@@ -302 +304 @@
 {
         errno_t rc;
-        long pos;
-
-        pos = ftell(parent->riffr->f);
-        if (pos < 0) {
-                rc = EIO;
-                goto error;
-        }
 
         rchunk->riffr = parent->riffr;
-        rchunk->ckstart = pos + 8;
+        rchunk->ckstart = parent->riffr->pos + 8;
         rc = riff_read_uint32(parent, &rchunk->ckid);
         if (rc != EOK)
@@ -402 +397 @@
 errno_t riff_rchunk_seek(riff_rchunk_t *rchunk, long offset, int whence)
 {
-        long pos;
         long dest;
         int rv;
@@ -414 +408 @@
                 break;
         case SEEK_CUR:
-                pos = ftell(rchunk->riffr->f);
-                if (pos < 0)
-                        return EIO;
-                dest = pos + offset;
+                dest = rchunk->riffr->pos + offset;
                 break;
         default:
@@ -432 +423 @@
                 return EIO;
 
+        rchunk->riffr->pos = dest;
         return EOK;
 }
@@ -482 +474 @@
 {
         long ckend;
+        uint8_t byte;
+        size_t nread;
+        errno_t rc;
 
         ckend = riff_rchunk_get_ndpos(rchunk);
-        if (fseek(rchunk->riffr->f, ckend, SEEK_SET) < 0)
-                return EIO;
+        if (rchunk->riffr->pos < ckend &&
+            ckend <= rchunk->riffr->pos + 512) {
+                /* (Buffered) reading is faster than seeking */
+                while (rchunk->riffr->pos < ckend) {
+                        rc = riff_read(rchunk, &byte, sizeof(byte), &nread);
+                        if (rc != EOK)
+                                return rc;
+
+                        if (nread != sizeof(byte))
+                                return EIO;
+                }
+
+        } else if (rchunk->riffr->pos != ckend) {
+                /* Need to seek (backwards or too far) */
+                if (fseek(rchunk->riffr->f, ckend, SEEK_SET) < 0)
+                        return EIO;
+                rchunk->riffr->pos = ckend;
+        }
 
         return EOK;
@@ -511 +522 @@
         long toread;
 
-        pos = ftell(rchunk->riffr->f);
-        if (pos < 0)
-                return EIO;
+        pos = rchunk->riffr->pos;
 
         ckend = riff_rchunk_get_end(rchunk);
@@ -529 +538 @@
                 return EIO;
 
+        rchunk->riffr->pos += *nread;
         return EOK;
 }