X-Git-Url: https://git.ucc.asn.au/?a=blobdiff_plain;f=ROM2%2Fxmodem.c;h=b164243b7d4225bae809139502fb9ccba606767f;hb=dc87be12e6cb8428ab33c0984c5f871e6e1c5587;hp=7615d9bff363c51e10592ca62f9124804286563c;hpb=db71d9706715bf39fa5c5696108019bacd8181fa;p=uccvend-snackrom.git

diff --git a/ROM2/xmodem.c b/ROM2/xmodem.c
index 7615d9b..b164243 100644
--- a/ROM2/xmodem.c
+++ b/ROM2/xmodem.c
@@ -21,6 +21,7 @@
 #include "chime.h"
 #include "sci.h"
 #include "xmodem.h"
+#include "crctab.h"
 
 /* These definitions are for xmodem protocol. */
 
@@ -51,43 +52,21 @@ readchar (int timeout)
   return 0;
 }
 
-#define CRC16 0x1021		/* Generator polynomial (X^16 + X^12 + X^5 + 1) */
-
-
-/* Call this to init the fast CRC-16 calculation table.  */
-
-static short crctab(u8 val) {
-      int i;
-      unsigned int crc;
-
-      crc = val << 8;
-
-      for (i = 0; i < 8; ++i)
-	{
-	  crc <<= 1;
-
-	  if (crc & 0x10000)
-	    crc ^= CRC16;
-	}
-
-	  return crc;
-}
-
 /* Calculate a CRC-16 for the LEN byte message pointed at by P.  */
-/* Pads with ^Z if necessary */
+/* Pads with ^Z up to 128 bytes if told to */
 
 static unsigned short
-docrc (unsigned char *p, int len)
+docrc (unsigned char *p, int len, bool pad)
 {
   int len2 = len;
   unsigned short crc = 0;
 
   while (len-- > 0)
-    crc = (crc << 8) ^ crctab((crc >> 8) ^ *p++);
-  if (len2 < 128) {
+    crc = (crc << 8) ^ crctab[(crc >> 8) ^ *p++];
+  if (pad && len2 < 128) {
     len = 128-len;
     while (len-- > 0)
-      crc = (crc << 8) ^ crctab((crc >> 8) ^ 0x1a);
+      crc = (crc << 8) ^ crctab[(crc >> 8) ^ 0x1a];
   }
 
   return crc;
@@ -183,7 +162,7 @@ xmodem_send_packet (const unsigned char *packet, int len)
     if (crcflag) {
       u16 crc;
 
-      crc = docrc ((unsigned char*)packet, len);
+      crc = docrc ((unsigned char*)packet, len, 1);
 
       s[0] = crc >> 8;
       s[1] = crc & 0xff;