Avoid dereferencing NULL pointer.

If a NULL pointer is passed, don't attempt to increment it.  This avoids
passing the now not-NULL pointer on and eventually segfaulting.  Also
remove some unnecessary temporary variables.

Change-Id: I268e225121aa283d59179bfae407ebf6959d3a4e
Signed-off-by: Darius Rad <darius@bluespec.com>
Reviewed-on: http://openocd.zylin.com/4550
Tested-by: jenkins
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>

diff --git a/src/jtag/drivers/jtag_vpi.c b/src/jtag/drivers/jtag_vpi.c
index a1787d496445815d9eba03fbada3234292a68de8..1a42b3a05f41b910603424cd703143f98c4f8011 100644 (file)
--- a/src/jtag/drivers/jtag_vpi.c
+++ b/src/jtag/drivers/jtag_vpi.c
@@ -204,23 +204,20 @@ static int jtag_vpi_queue_tdi_xfer(uint8_t *bits, int nb_bits, int tap_shift)
 static int jtag_vpi_queue_tdi(uint8_t *bits, int nb_bits, int tap_shift)
 {
        int nb_xfer = DIV_ROUND_UP(nb_bits, XFERT_MAX_SIZE * 8);
-       uint8_t *xmit_buffer = bits;
-       int xmit_nb_bits = nb_bits;
-       int i = 0;
        int retval;
 
        while (nb_xfer) {
-
                if (nb_xfer ==  1) {
-                       retval = jtag_vpi_queue_tdi_xfer(&xmit_buffer[i], xmit_nb_bits, tap_shift);
+                       retval = jtag_vpi_queue_tdi_xfer(bits, nb_bits, tap_shift);
                        if (retval != ERROR_OK)
                                return retval;
                } else {
-                       retval = jtag_vpi_queue_tdi_xfer(&xmit_buffer[i], XFERT_MAX_SIZE * 8, NO_TAP_SHIFT);
+                       retval = jtag_vpi_queue_tdi_xfer(bits, XFERT_MAX_SIZE * 8, NO_TAP_SHIFT);
                        if (retval != ERROR_OK)
                                return retval;
-                       xmit_nb_bits -= XFERT_MAX_SIZE * 8;
-                       i += XFERT_MAX_SIZE;
+                       nb_bits -= XFERT_MAX_SIZE * 8;
+                       if (bits)
+                               bits += XFERT_MAX_SIZE;
                }
 
                nb_xfer--;