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Optimizations for better write performance.

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fputs() now works almost exactly like fwrite(), except that it's dealing with a NUL-terminated string.
This commit is contained in:
obarthel
2019-08-24 14:00:03 +02:00
parent 914ef57844
commit 4a01746be2
1 changed files with 156 additions and 12 deletions
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168
library/stdio_fputs.c
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@ -1,10 +1,8 @@
/*
* $Id: stdio_fputs.c,v 1.7 2006-01-08 12:04:24 obarthel Exp $
*
* :ts=4
*
* Portable ISO 'C' (1994) runtime library for the Amiga computer
* Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
* Copyright (c) 2002-2019 by Olaf Barthel <obarthel (at) gmx.net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -47,8 +45,8 @@ int
fputs(const char *s, FILE *stream)
{
struct iob * file = (struct iob *)stream;
size_t total_size;
int result = EOF;
int buffer_mode;
int c;
ENTER();
@ -77,17 +75,162 @@ fputs(const char *s, FILE *stream)
assert( FLAG_IS_SET(file->iob_Flags,IOBF_IN_USE) );
assert( file->iob_BufferSize > 0 );
buffer_mode = (file->iob_Flags & IOBF_BUFFER_MODE);
if(buffer_mode == IOBF_BUFFER_MODE_NONE)
buffer_mode = IOBF_BUFFER_MODE_LINE;
if(__fputc_check(stream) < 0)
goto out;
while((c = (*s++)) != '\0')
total_size = strlen(s);
if(total_size > 0)
{
if(__putc(c,stream,buffer_mode) == EOF)
goto out;
int buffer_mode;
/* We perform line buffering to improve readability of the
buffered text if buffering was disabled and the output
goes to an interactive stream. */
buffer_mode = (file->iob_Flags & IOBF_BUFFER_MODE);
if(buffer_mode == IOBF_BUFFER_MODE_NONE)
{
struct fd * fd = __fd[file->iob_Descriptor];
__fd_lock(fd);
if(FLAG_IS_SET(fd->fd_Flags,FDF_IS_INTERACTIVE))
buffer_mode = IOBF_BUFFER_MODE_LINE;
__fd_unlock(fd);
}
if (buffer_mode == IOBF_BUFFER_MODE_LINE)
{
while(total_size > 0)
{
/* Is there still room in the write buffer to store
more of the string? */
if(file->iob_BufferWriteBytes < file->iob_BufferSize)
{
unsigned char * buffer = &file->iob_Buffer[file->iob_BufferWriteBytes];
size_t num_buffer_bytes;
const char * lf;
/* Store only as many characters as will fit into the write buffer. */
num_buffer_bytes = file->iob_BufferSize - file->iob_BufferWriteBytes;
if(total_size < num_buffer_bytes)
num_buffer_bytes = total_size;
/* Try to find a line feed in the string. If there is one,
reduce the number of characters to write to the sequence
which ends with the line feed character. */
lf = memchr(s, '\n', num_buffer_bytes);
if(lf != NULL)
num_buffer_bytes = lf + 1 - s;
memmove(buffer, s, num_buffer_bytes);
s += num_buffer_bytes;
file->iob_BufferWriteBytes += num_buffer_bytes;
/* Write the buffer to disk if it's full or contains a line feed. */
if((lf != NULL || __iob_write_buffer_is_full(file)) && __flush_iob_write_buffer(file) < 0)
{
/* Abort with error. */
goto out;
}
/* Stop as soon as no further data needs to be written. */
total_size -= num_buffer_bytes;
if(total_size == 0)
break;
/* If there is again room in the output buffer,
repeat this optimization. */
if(file->iob_BufferWriteBytes < file->iob_BufferSize)
continue;
}
c = (*s++);
if(__putc_line_buffered(c,(FILE *)file) == EOF)
goto out;
total_size--;
}
}
else if (buffer_mode == IOBF_BUFFER_MODE_NONE)
{
ssize_t num_bytes_written;
/* We bypass the buffer entirely. */
num_bytes_written = write(file->iob_Descriptor, s, total_size);
if(num_bytes_written == -1)
{
SET_FLAG(file->iob_Flags,IOBF_ERROR);
goto out;
}
}
else
{
while(total_size > 0)
{
/* If there is more data to be written than the write buffer will hold
and the write buffer is empty anyway, then we'll bypass the write
buffer entirely. */
if(file->iob_BufferWriteBytes == 0 && total_size >= (size_t)file->iob_BufferSize)
{
ssize_t num_bytes_written;
/* We bypass the buffer entirely. */
num_bytes_written = write(file->iob_Descriptor, s, total_size);
if(num_bytes_written == -1)
{
SET_FLAG(file->iob_Flags,IOBF_ERROR);
goto out;
}
break;
}
/* Is there still room in the write buffer to store
more of the string? */
if(file->iob_BufferWriteBytes < file->iob_BufferSize)
{
unsigned char * buffer = &file->iob_Buffer[file->iob_BufferWriteBytes];
size_t num_buffer_bytes;
/* Store only as many characters as will fit into the write buffer. */
num_buffer_bytes = file->iob_BufferSize - file->iob_BufferWriteBytes;
if(total_size < num_buffer_bytes)
num_buffer_bytes = total_size;
memmove(buffer, s, num_buffer_bytes);
s += num_buffer_bytes;
file->iob_BufferWriteBytes += num_buffer_bytes;
/* Write a full buffer to disk. */
if(__iob_write_buffer_is_full(file) && __flush_iob_write_buffer(file) < 0)
{
/* Abort with error. */
goto out;
}
/* Stop as soon as no further data needs to be written. */
total_size -= num_buffer_bytes;
if(total_size == 0)
break;
/* If there is again room in the output buffer,
try this optimization again. */
if(file->iob_BufferWriteBytes < file->iob_BufferSize)
continue;
}
c = (*s++);
if(__putc_fully_buffered(c,(FILE *)file) == EOF)
goto out;
total_size--;
}
}
}
result = OK;
@ -107,7 +250,8 @@ fputs(const char *s, FILE *stream)
}
}
funlockfile(stream);
if(stream != NULL)
funlockfile(stream);
RETURN(result);
return(result);