libmocha/source/devoptab/devoptab_fsa_read.cpp
2022-06-17 18:26:55 +02:00

77 lines
2.2 KiB
C++

#include "devoptab_fs.h"
#include "logger.h"
#include <mutex>
#include <sys/param.h>
ssize_t __fsa_read(struct _reent *r, void *fd, char *ptr, size_t len) {
if (!fd || !ptr) {
r->_errno = EINVAL;
return -1;
}
// Check that the file was opened with read access
__fsa_file_t *file = (__fsa_file_t *) fd;
if ((file->flags & O_ACCMODE) == O_WRONLY) {
r->_errno = EBADF;
return -1;
}
// cache-aligned, cache-line-sized
__attribute__((aligned(0x40))) uint8_t alignedBuffer[0x40];
auto *deviceData = (FSADeviceData *) r->deviceData;
std::lock_guard<FastLockWrapper> lock(deviceData->mutex);
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;
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 {
// read whole cache lines
size &= ~0x3F;
}
// Limit each request to 1 MiB
if (size > 0x100000) {
size = 0x100000;
}
FSError status = FSAReadFile(deviceData->clientHandle, tmp, 1, size, file->fd, 0);
if (status < 0) {
DEBUG_FUNCTION_LINE_ERR("FSAReadFile(0x%08X, 0x%08X, 1, 0x%08X, 0x%08X, 0) failed: %s", deviceData->clientHandle, tmp, size, file->fd, FSAGetStatusStr(status));
if (bytesRead != 0) {
return bytesRead; // error after partial read
}
r->_errno = __fsa_translate_error(status);
return -1;
}
if (tmp == alignedBuffer) {
memcpy(ptr, alignedBuffer, status);
}
bytesRead += status;
ptr += status;
if ((size_t) status != size) {
return bytesRead; // partial read
}
}
return bytesRead;
}