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Added lseek()

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@518 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Björn Stenberg 2002-05-08 15:16:02 +00:00
parent 6a63f911fe
commit 1c3217909b
3 changed files with 145 additions and 19 deletions
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72
firmware/common/file.c
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@ -100,7 +100,7 @@ int open(char* pathname, int flags)
return -1;
}
openfiles[fd].cacheoffset = 0;
openfiles[fd].cacheoffset = -1;
openfiles[fd].fileoffset = 0;
openfiles[fd].busy = TRUE;
return fd;
@ -127,7 +127,7 @@ int read(int fd, void* buf, int count)
count = openfiles[fd].size - openfiles[fd].fileoffset;
/* any head bytes? */
if ( openfiles[fd].cacheoffset ) {
if ( openfiles[fd].cacheoffset != -1 ) {
int headbytes;
int offs = openfiles[fd].cacheoffset;
if ( count <= SECTOR_SIZE - openfiles[fd].cacheoffset ) {
@ -138,7 +138,7 @@ int read(int fd, void* buf, int count)
}
else {
headbytes = SECTOR_SIZE - openfiles[fd].cacheoffset;
openfiles[fd].cacheoffset = 0;
openfiles[fd].cacheoffset = -1;
}
/* eof? */
@ -169,7 +169,7 @@ int read(int fd, void* buf, int count)
count=0;
}
openfiles[fd].cacheoffset = 0;
openfiles[fd].cacheoffset = -1;
}
}
@ -195,6 +195,70 @@ int read(int fd, void* buf, int count)
return nread;
}
int lseek(int fd, int offset, int whence)
{
int pos;
int newsector;
int oldsector;
int sectoroffset;
int rc;
if ( !openfiles[fd].busy ) {
errno = EBADF;
return -1;
}
switch ( whence ) {
case SEEK_SET:
pos = offset;
break;
case SEEK_CUR:
pos = openfiles[fd].fileoffset + offset;
break;
case SEEK_END:
pos = openfiles[fd].size - offset;
break;
default:
errno = EINVAL;
return -1;
}
if ( (pos < 0) ||
(pos > openfiles[fd].size) ) {
errno = EINVAL;
return -1;
}
/* new sector? */
newsector = pos / SECTOR_SIZE;
oldsector = openfiles[fd].fileoffset / SECTOR_SIZE;
sectoroffset = pos % SECTOR_SIZE;
if ( (newsector != oldsector) ||
((openfiles[fd].cacheoffset==-1) && sectoroffset) ) {
if ( newsector != oldsector ) {
rc = fat_seek(&(openfiles[fd].fatfile), newsector);
if ( rc < 0 ) {
errno = EIO;
return -1;
}
}
rc = fat_read(&(openfiles[fd].fatfile), 1,
&(openfiles[fd].cache));
if ( rc < 0 ) {
errno = EIO;
return -1;
}
}
openfiles[fd].cacheoffset = sectoroffset;
openfiles[fd].fileoffset = pos;
return pos;
}
/*
* local variables:
* eval: (load-file "../rockbox-mode.el")