fix return value for error.

[proxmark3-svn] / common / usb_cdc.c

diff --git a/common/usb_cdc.c b/common/usb_cdc.c
index ccbb3c50e91389a4d733e25f75c7f94e50e77ef5..7fd2933c322463f5d5790b9397d5c7aeb8d3b72a 100644 (file)
--- a/common/usb_cdc.c
+++ b/common/usb_cdc.c
@@ -293,31 +293,47 @@ bool usb_poll()
   return (pUdp->UDP_CSR[AT91C_EP_OUT] & btReceiveBank);\r
 }\r
 \r
+/**\r
+       In github PR #129, some users appears to get a false positive from\r
+       usb_poll, which returns true, but the usb_read operation\r
+       still returns 0.\r
+       This check is basically the same as above, but also checks\r
+       that the length available to read is non-zero, thus hopefully fixes the\r
+       bug.\r
+**/\r
+bool usb_poll_validate_length()\r
+{\r
+\r
+       if (!usb_check()) return false;\r
+       if (!(pUdp->UDP_CSR[AT91C_EP_OUT] & btReceiveBank)) return false;\r
+       return (pUdp->UDP_CSR[AT91C_EP_OUT] >> 16) >  0;\r
+}\r
+\r
 //*----------------------------------------------------------------------------\r
 //* \fn    usb_read\r
 //* \brief Read available data from Endpoint OUT\r
 //*----------------------------------------------------------------------------\r
 uint32_t usb_read(byte_t* data, size_t len) {\r
-  byte_t bank = btReceiveBank;\r
+       byte_t bank = btReceiveBank;\r
        uint32_t packetSize, nbBytesRcv = 0;\r
-  uint32_t time_out = 0;\r
+       uint32_t time_out = 0;\r
   \r
        while (len)  {\r
                if (!usb_check()) break;\r
 \r
                if ( pUdp->UDP_CSR[AT91C_EP_OUT] & bank ) {\r
                        packetSize = MIN(pUdp->UDP_CSR[AT91C_EP_OUT] >> 16, len);\r
-      len -= packetSize;\r
+                       len -= packetSize;\r
                        while(packetSize--)\r
                                data[nbBytesRcv++] = pUdp->UDP_FDR[AT91C_EP_OUT];\r
                        pUdp->UDP_CSR[AT91C_EP_OUT] &= ~(bank);\r
                        if (bank == AT91C_UDP_RX_DATA_BK0) {\r
                                bank = AT91C_UDP_RX_DATA_BK1;\r
-      } else {\r
+                       } else {\r
                                bank = AT91C_UDP_RX_DATA_BK0;\r
-      }\r
+                       }\r
                }\r
-    if (time_out++ == 0x1fff) break;\r
+               if (time_out++ == 0x1fff) break;\r
        }\r
 \r
        btReceiveBank = bank;\r
@@ -346,7 +362,7 @@ uint32_t usb_write(const byte_t* data, const size_t len) {
                cpt = MIN(length, AT91C_EP_IN_SIZE-1);\r
                length -= cpt;\r
                while (cpt--) pUdp->UDP_FDR[AT91C_EP_IN] = *data++;\r
-               // Wait for the the first bank to be sent\r
+               // Wait for the first bank to be sent\r
                while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {\r
                        if (!usb_check()) return length;\r
     }\r