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Optimize buffer_streamfile EOF reads and fix get_offset behaviour

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This commit is contained in:
bnnm 2018-08-19 22:31:12 +02:00
parent 2e6f6c8176
commit a5656eaa2f
1 changed files with 24 additions and 30 deletions
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54
src/streamfile.c
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@ -107,8 +107,8 @@ static size_t get_size_stdio(STDIOSTREAMFILE * streamfile) {
return streamfile->filesize;
}
static off_t get_offset_stdio(STDIOSTREAMFILE *streamFile) {
return streamFile->offset;
static off_t get_offset_stdio(STDIOSTREAMFILE *streamfile) {
return streamfile->offset;
}
static void get_name_stdio(STDIOSTREAMFILE *streamfile,char *buffer,size_t length) {
@ -215,7 +215,8 @@ typedef struct {
STREAMFILE sf;
STREAMFILE *inner_sf;
off_t offset; /* current buffer data start */
off_t offset; /* last read offset (info) */
off_t buffer_offset; /* current buffer data start */
uint8_t * buffer; /* data buffer */
size_t buffersize; /* max buffer size */
size_t validsize; /* current buffer size */
@ -230,9 +231,9 @@ static size_t buffer_read(BUFFER_STREAMFILE *streamfile, uint8_t * dest, off_t o
return 0;
/* is the part of the requested length in the buffer? */
if (offset >= streamfile->offset && offset < streamfile->offset + streamfile->validsize) {
if (offset >= streamfile->buffer_offset && offset < streamfile->buffer_offset + streamfile->validsize) {
size_t length_to_read;
off_t offset_into_buffer = offset - streamfile->offset;
off_t offset_into_buffer = offset - streamfile->buffer_offset;
length_to_read = streamfile->validsize - offset_into_buffer;
if (length_to_read > length)
@ -245,27 +246,21 @@ static size_t buffer_read(BUFFER_STREAMFILE *streamfile, uint8_t * dest, off_t o
dest += length_to_read;
}
/* What would make more sense here is to read the whole request
* at once into the dest buffer, as it must be large enough, and then
* copy some part of that into our own buffer.
* The destination buffer is supposed to be much smaller than the
* STREAMFILE buffer, though. Maybe we should only ever return up
* to the buffer size to avoid having to deal with things like this
* which are outside of my intended use. */
/* read the rest of the requested length */
while (length > 0) {
size_t length_to_read, length_read;
streamfile->validsize = 0; /* buffer is empty now */
size_t length_to_read;
/* request outside file: ignore to avoid seek/read */
if (offset > streamfile->filesize) {
streamfile->offset = streamfile->filesize;
VGM_LOG_ONCE("ERROR: reading over filesize 0x%x @ 0x%lx + 0x%x (buggy meta?)\n", streamfile->filesize, offset, length);
return length_read_total; /* partially-read buffer */
/* ignore requests at EOF */
if (offset >= streamfile->filesize) {
//offset = streamfile->filesize; /* seems fseek doesn't clamp offset */ //todo once
VGM_ASSERT_ONCE(offset > streamfile->filesize, "BUFFER: reading over filesize 0x%x @ 0x%lx + 0x%x\n", streamfile->filesize, offset, length);
break;
}
streamfile->offset = offset;
/* fill the buffer (being here means offset is outside buffer thus empty) */
streamfile->buffer_offset = offset;
streamfile->validsize = streamfile->inner_sf->read(streamfile->inner_sf, streamfile->buffer, streamfile->buffer_offset, streamfile->buffersize);
/* decide how much must be read this time */
if (length > streamfile->buffersize)
@ -273,31 +268,30 @@ static size_t buffer_read(BUFFER_STREAMFILE *streamfile, uint8_t * dest, off_t o
else
length_to_read = length;
/* fill the buffer */
length_read = streamfile->inner_sf->read(streamfile->inner_sf, streamfile->buffer, streamfile->offset, streamfile->buffersize);
streamfile->validsize = length_read;
/* if we can't get enough to satisfy the request (EOF) we give up */
if (length_read < length_to_read) {
memcpy(dest,streamfile->buffer,length_read);
return length_read_total + length_read; /* partially-read buffer */
/* give up on partial reads (EOF) */
if (streamfile->validsize < length_to_read) {
memcpy(dest,streamfile->buffer,streamfile->validsize);
offset += streamfile->validsize;
length_read_total += streamfile->validsize;
break;
}
/* use the new buffer */
memcpy(dest,streamfile->buffer,length_to_read);
offset += length_to_read;
length_read_total += length_to_read;
length -= length_to_read;
dest += length_to_read;
offset += length_to_read;
}
streamfile->offset = offset; /* last fread offset */
return length_read_total;
}
static size_t buffer_get_size(BUFFER_STREAMFILE * streamfile) {
return streamfile->filesize; /* cache */
}
static size_t buffer_get_offset(BUFFER_STREAMFILE * streamfile) {
return streamfile->offset; /* cache */ //todo internal offset?
return streamfile->offset; /* cache */
}
static void buffer_get_name(BUFFER_STREAMFILE *streamfile, char *buffer, size_t length) {
streamfile->inner_sf->get_name(streamfile->inner_sf, buffer, length); /* default */