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Buffered SD File Reads/Writes

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This commit is contained in:
HCStealth 2014-12-07 18:00:43 -08:00
parent 6a195608aa
commit 93847b0817
1 changed files with 158 additions and 23 deletions
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179
libctru/source/sdmc_dev.c
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@ -5,6 +5,8 @@
#include <sys/iosupport.h>
#include <sys/param.h>
#include <stdio.h>
#include <dirent.h>
#include <string.h>
#include <3ds.h>
@ -39,12 +41,25 @@ static int sdmc_fchmod(struct _reent *r, int fd, mode_t mode);
/*! @cond INTERNAL */
#define SDMC_FILEBUFFSIZE 0x4000 /* Size of file data buffer */
#define SDMC_FILEBUFFMASK (-SDMC_FILEBUFFSIZE) /* For calculating the start of the buffer's current chunk */
#define SDMC_FILEOFFMASK (SDMC_FILEBUFFSIZE-1) /* For calculating the start offset within the buffer */
#define SDMC_BUFFINVALID 0xFFFFFFFF /* To indicate that a buffer has not actually been loaded yet */
/*! Open file struct */
typedef struct
{
Handle fd; /*! CTRU handle */
int flags; /*! Flags used in open(2) */
u64 offset; /*! Current file offset */
u8 buffer[SDMC_FILEBUFFSIZE]; /* File data buffer for speed-of-access */
u64 boffset; /* File start offset of the current buffered chunk */
u32 bsize; /* Amount of valid data in the buffer before EOF */
u64 size; /* Size of the file in bytes*/
} sdmc_file_t;
/*! Open directory struct */
@ -251,6 +266,19 @@ sdmc_open(struct _reent *r,
file->fd = fd;
file->flags = (flags & (O_ACCMODE|O_APPEND|O_SYNC));
file->offset = 0;
/* initialize buffer offset to buffer on first-read/write */
file->boffset = SDMC_BUFFINVALID;
file->bsize = 0;
/* record the file's size */
rc = FSFILE_GetSize(file->fd, &file->size);
if(rc != 0)
{
r->_errno = rc;
return -1;
}
return 0;
}
@ -272,9 +300,22 @@ sdmc_close(struct _reent *r,
{
Result rc;
u32 bytes;
/* get pointer to our data */
sdmc_file_t *file = (sdmc_file_t*)fd;
/* check if the file was opened with write access */
if((file->flags & O_ACCMODE) != O_RDONLY)
{
/* flush the current buffer */
if((rc = FSFILE_Write(file->fd, &bytes, file->boffset, file->buffer, file->bsize, FS_WRITE_FLUSH)) != 0)
{
r->_errno = rc;
return -1;
}
}
rc = FSFILE_Close(file->fd);
if(rc == 0)
return 0;
@ -304,6 +345,10 @@ sdmc_write(struct _reent *r,
u32 sync = 0;
u64 offset;
u32 start;
u32 curlen;
u32 total;
/* get pointer to our data */
sdmc_file_t *file = (sdmc_file_t*)fd;
@ -316,7 +361,7 @@ sdmc_write(struct _reent *r,
/* check if this is synchronous or not */
if(file->flags & O_SYNC)
sync = 0x10001;
sync = FS_WRITE_FLUSH;
/* initialize offset */
offset = file->offset;
@ -331,24 +376,63 @@ sdmc_write(struct _reent *r,
}
}
/* TODO: Copy to internal buffer and write in chunks.
* You cannot write from read-only memory.
*/
/* initialize buffer start position, copy length, and total copied count */
start = offset & SDMC_FILEOFFMASK;
curlen = SDMC_FILEBUFFSIZE-start;
total = 0;
/* write the data */
rc = FSFILE_Write(file->fd, &bytes, offset, (u32*)ptr, (u32)len, sync);
if(rc == 0)
/* if the target location is not in the currently-buffered chunk, save the current buffer and load the target chunk */
if(file->boffset != (offset & SDMC_FILEBUFFMASK))
{
/* update current file offset; if O_APPEND, this moves it to the
* new end-of-file
*/
file->offset = offset + bytes;
return (ssize_t)bytes;
}
/* if there is a valid buffer */
if(file->boffset != SDMC_BUFFINVALID)
{
buffernext:
/* flush the current buffer */
if((rc = FSFILE_Write(file->fd, &bytes, file->boffset, file->buffer, file->bsize, sync)) != 0)
{
r->_errno = rc;
return -1;
}
}
/* buffer the target chunk */
file->boffset = offset & SDMC_FILEBUFFMASK;
if((rc = FSFILE_Read(file->fd, &file->bsize, file->boffset, file->buffer, SDMC_FILEBUFFSIZE)) != 0)
{
r->_errno = rc;
return -1;
}
}
// else
// bytes = file->boffset + start;
if(curlen > len)
curlen = len;
memcpy(file->buffer+start, ptr, curlen);
total += curlen;
offset += curlen;
if((offset - file->boffset) > file->bsize)
file->bsize = offset - file->boffset;
if((len -= curlen) > 0)
{
ptr += curlen;
start = 0;
if(len > SDMC_FILEBUFFSIZE)
curlen = SDMC_FILEBUFFSIZE;
else
curlen = len;
goto buffernext;
}
file->offset = offset;
/* return the total number of bytes that were actually copied */
return (ssize_t)total;
}
/*! Read from an open file
*
@ -367,7 +451,11 @@ sdmc_read(struct _reent *r,
size_t len)
{
Result rc;
u32 bytes;
// u32 bytes;
u32 start;
u32 curlen;
u32 total;
/* get pointer to our data */
sdmc_file_t *file = (sdmc_file_t*)fd;
@ -379,18 +467,56 @@ sdmc_read(struct _reent *r,
return -1;
}
/* read the data */
rc = FSFILE_Read(file->fd, &bytes, file->offset, (u32*)ptr, (u32)len);
if(rc == 0)
{
/* update current file offset */
file->offset += bytes;
return (ssize_t)bytes;
}
if((file->offset + len) > file->size)
if((len = (file->size - file->offset)) <= 0)
return(0);
/* initialize buffer start position, copy length, and total copied count */
start = file->offset & SDMC_FILEOFFMASK;
curlen = SDMC_FILEBUFFSIZE-start;
total = 0;
/* if the requested data does not reside in the currently-buffered chunk, load the buffer */
if(file->boffset != (file->offset & SDMC_FILEBUFFMASK))
{
buffernext:
file->boffset = file->offset & SDMC_FILEBUFFMASK;
/* read the data */
if((rc = FSFILE_Read(file->fd, &file->bsize, file->boffset, file->buffer, SDMC_FILEBUFFSIZE)) != 0)
{
r->_errno = rc;
return -1;
}
}
// else
// bytes = file->boffset + start;
if(curlen > len)
curlen = len;
if(curlen > file->bsize)
curlen = file->bsize;
memcpy(ptr, file->buffer+start, curlen);
total += curlen;
file->offset += curlen;
if((len -= curlen) > 0)
{
if(curlen + start == SDMC_FILEBUFFSIZE)
{
ptr += curlen;
start = 0;
if(len > SDMC_FILEBUFFSIZE)
curlen = SDMC_FILEBUFFSIZE;
else
curlen = len;
goto buffernext;
}
}
/* return the total number of bytes that were actually copied */
return (ssize_t)total;
}
/*! Update an open file's current offset
*
@ -855,9 +981,18 @@ sdmc_fsync(struct _reent *r,
{
Result rc;
u32 bytes;
/* get pointer to our data */
sdmc_file_t *file = (sdmc_file_t*)fd;
/* flush the current buffer */
if((rc = FSFILE_Write(file->fd, &bytes, file->boffset, file->buffer, file->bsize, FS_WRITE_FLUSH)) != 0)
{
r->_errno = rc;
return -1;
}
rc = FSFILE_Flush(file->fd);
if(rc == 0)
return 0;