(require mzlib/foreign) 
(unsafe!)

(define winscard (ffi-lib "winscard"))

;; typedef unsigned long DWORD;
(define _DWORD _ulong)

;; typedef long LONG;
(define _LONG _long)

;; SCARDHANDLE should be an opaque pointer
;; - for type safety -
;; but we can do with 32 bit integer too.
(define _SCARDHANDLE _int)

#| The SCARD_IO_REQUEST structure begins a protocol control information structure.

typedef struct {  
    DWORD dwProtocol;  
    DWORD cbPciLength;
} SCARD_IO_REQUEST;
|#
(define-cstruct _SCARD_IO_REQUEST ((dwProtocol _DWORD)
                                   (cbPciLength _DWORD)))

#| The SCardTransmit function sends a service request to the smart card and expects to receive data back from the card.

/* Tags for input and output parameters. */
#define IN 
#define OUT

LONG SCardTransmit(
    IN     SCARDHANDLE hCard,
    IN     SCARD_IO_REQUEST* pioSendPci,
    IN     const BYTE* pbSendBuffer,
    IN     DWORD cbSendLength, // Size of pbSendBuffer.
    IN OUT SCARD_IO_REQUEST* pioRecvPci, // It can be NULL.
    OUT    BYTE* pbRecvBuffer,
    IN OUT DWORD* pcbRecvLength);
|#
(define SCardTransmit
  (get-ffi-obj "SCardTransmit"
               winscard
               (_fun
                ;; IN SCARDHANDLE hCard
                (hCard :          _SCARDHANDLE)                  
                ;; IN SCARD_IO_REQUEST* pioSendPci
                (pioSendPci :    (_ptr i _SCARD_IO_REQUEST))     
                ;; IN const BYTE* pbSendBuffer
                (pbSendBuffer :  (_vector i _byte))              
                ;; IN DWORD cbSendLength // Size of pbSendBuffer.
                (_DWORD =        (vector-length pbSendBuffer))
                ;; IN OUT SCARD_IO_REQUEST* pioRecvPci
                (ioRecvPci :     _SCARD_IO_REQUEST-pointer/null)
                ;; OUT BYTE* pbRecvBuffer
                (pbRecvBuffer :  (_vector o _byte cbRecvLength))
                ;; IN OUT DWORD* pcbRecvLength
                (cbRecvLength :  (_ptr io _DWORD))
                ;; return code
                -> (error : _LONG) 
                )))


(SCardTransmit 1 
               (make-SCARD_IO_REQUEST 2 8)
               (make-vector 4 0)
               ;; cbSendLength AUTOMATICALLY GENERATED.
               (make-SCARD_IO_REQUEST 2 8)
               ;; pbRecvBuffer SKIPPED SINCE IT IS AN OUTPUT PARAMETER.
               4
               )