Multi Channel DMA Intel® FPGA IP for PCI Express User Guide
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8.3.7. API List
| Function Description | Prototype | Return Values | 
|---|---|---|
| Channel acquisition | int open(const char *pathname, int flags, mode_t mode); | File descriptor if successful, negative otherwise | 
| Function Description | Prototype | Return Values | 
|---|---|---|
| Free the allocated channel | int close(int fd); | zero on success -1 otherwise, errno is set appropriately | 
| Function Description | Prototype | Return Values | 
|---|---|---|
| Request submission for D2H transfer |   ssize_t read(int fd, void *buf, int count); buf : DMA buffer memory starting address count: size of the DMA transfer data  |  
          number of bytes read if successful -1 otherwise, errno is set appropriately  |  
       
| Function Description | Prototype | Return Values | 
|---|---|---|
| Request submission for H2D transfer |   ssize_t write(int fd, void *buf, int count); buf: DMA buffer memory starting address count: size of the DMA transfer data  |  
        number of bytes written if successful -1 otherwise, errno is set appropriately | 
| Function Description | Prototype | Return Values | 
|---|---|---|
| Request submission for H2D transfer in batches | ssize_t readv(int fd, const struct iovec *iov, int iovcnt); |   On success, readv() return the number of bytes read On error, -1 is returned, and errno is set appropriately  |  
       
| Function Description | Prototype | Return Values | 
|---|---|---|
| Request submission for D2H transfer in batches | ssize_t writev(int fd, const struct iovec *iov, int iovcnt); |   On success, writev() return the number of bytes written On error, -1 is returned, and errno is set appropriately  |  
       
| Function Description | Prototype | Return Values | 
|---|---|---|
| Write Back poll |   int poll(struct pollfd *fds, nfds_t nfds, int timeout); 
          Special support of events: 
            
  |  
          On success, poll() returns a nonnegative value which is the number of elements in the pollfds whose revents fields have been set to a nonzero value (indicating an event or an error). A return value of zero indicates that the system call timed out before any file descriptors became read. On error, -1 is returned, and errno is set to indicate the cause of the error.  |