int
read(void *f, void *data, int len)
{
File *fp = f;
Fat *fat = fp->fat;
if(fp->len > 0 && fp->rp >= fp->ep){
if(fp->clust != ~0U){
if(fp->lbaoff % fat->clustsize == 0){
if((fp->clust >> 4) == fat->eofmark)
return -1;
fp->lbaoff = (fp->clust - 2) * fat->clustsize;
fp->clust = readnext(fp, fp->clust);
fp->lba = fp->lbaoff + fat->datalba;
}
fp->lbaoff++;
}
if(readsect(fat->drive, fp->lba++, fp->rp = fp->buf))
return -1;
}
if(fp->len < len)
len = fp->len;
if(len > (fp->ep - fp->rp))
len = fp->ep - fp->rp;
memmove(data, fp->rp, len);
fp->rp += len;
fp->len -= len;
return len;
}
// number of bytes available in the receive buffer
int usb_serial_class::available()
{
uint8_t c;
c = prev_byte; // assume 1 byte static volatile access is atomic
if (c) return 1;
c = readnext();
if (c) {
prev_byte = c;
return 1;
}
return 0;
}
int usb_serial_class::peek()
{
uint8_t c;
c = prev_byte;
if (c) return c;
c = readnext();
if (c) {
prev_byte = c;
return c;
}
return -1;
}
// get the next character, or -1 if nothing received
int usb_serial_class::read(void)
{
uint8_t c;
c = prev_byte;
if (c) {
prev_byte = 0;
return c;
}
c = readnext();
if (c) return c;
return -1;
}
char * ag_readnext(unsigned dbh, int foo)
{ return readnext(h2p(dbh),foo);
}
