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simplify code

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This commit is contained in:
Dave Murphy 2022-05-26 22:43:10 +01:00
parent f919d6b65b
commit b47c3b01cd
1 changed files with 34 additions and 32 deletions
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66
libraries/wutdevoptab/devoptab_fs_read.c
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@ -1,62 +1,64 @@
#include "devoptab_fs.h"
#include <sys/param.h>
ssize_t __wut_fs_read(struct _reent *r, void *fd, char *ptr, size_t len) {
FSStatus status = 0;
FSCmdBlock cmd;
size_t bytesRead = 0;
size_t partSize[3];
__wut_fs_file_t *file = (__wut_fs_file_t *) fd;
__attribute__((aligned(0x40))) uint8_t alignedBuffer[0x40];
if (!fd || !ptr) {
r->_errno = EINVAL;
return -1;
}
FSInitCmdBlock(&cmd);
// Check that the file was opened with read access
__wut_fs_file_t *file = (__wut_fs_file_t *) fd;
if ((file->flags & O_ACCMODE) == O_WRONLY) {
r->_errno = EBADF;
return -1;
}
partSize[0] = (0x40 - ((uintptr_t)ptr & 0x3f)) & 0x3f;
if (partSize[0] > len) partSize[0] = len;
partSize[1] = len - partSize[0];
partSize[2] = partSize[1] & 0x3f;
partSize[1] -= partSize[2];
// cache-aligned, cache-line-sized
__attribute__((aligned(0x40))) uint8_t alignedBuffer[0x40];
if (partSize[0] + partSize[2] <= 0x40 && partSize[1] == 0) {
partSize[0] += partSize[2];
partSize[2] = 0;
}
FSCmdBlock cmd;
FSInitCmdBlock(&cmd);
uint8_t *tmp;
size_t bytesRead = 0;
while (bytesRead < len) {
// only use input buffer if cache-aligned and read size is a multiple of cache line size
// otherwise read into alignedBuffer
uint8_t *tmp = (uint8_t*) ptr;
size_t size = len - bytesRead;
for (int part=0; part<3; part++) {
if (!partSize[0]) continue;
if (part == 1) {
tmp = (uint8_t *)ptr;
if ((uintptr_t) ptr & 0x3F) {
// read partial cache-line front-end
tmp = alignedBuffer;
size = MIN(size, 0x40 - ((uintptr_t) ptr & 0x3F));
} else if (size < 0x40) {
// read partial cache-line back-end
tmp = alignedBuffer;
} else {
tmp = alignedBuffer;
// read whole cache lines
size &= ~0x3F;
}
status = FSReadFile(__wut_devoptab_fs_client, &cmd, tmp, 1, partSize[part], file->fd, 0, FS_ERROR_FLAG_ALL);
FSStatus status = FSReadFile(__wut_devoptab_fs_client, &cmd, tmp, 1, size,
file->fd, 0, FS_ERROR_FLAG_ALL);
if (status < 0) {
if (bytesRead != 0)
return bytesRead; // error after partial read
r->_errno = __wut_fs_translate_error(status);
return -1;
}
if (part != 1) memcpy(ptr, alignedBuffer, status);
if (tmp == alignedBuffer)
memcpy(ptr, alignedBuffer, status);
bytesRead += status;
ptr += status;
if (status != partSize[part]) return bytesRead;
if (status != size)
return bytesRead; // partial read
}
return bytesRead;