[R-gregmisc-users] SF.net SVN: r-gregmisc:[1841] trunk/SASxport/src/ieee2ibm.c

[<wa...@us...>]

Revision: 1841
          http://sourceforge.net/p/r-gregmisc/code/1841
Author:   warnes
Date:     2014-07-18 18:37:51 +0000 (Fri, 18 Jul 2014)
Log Message:
-----------
Make sure all left shifts are explicitly typed as unsigned in to avoid
undefined behavior.

Modified Paths:
--------------
    trunk/SASxport/src/ieee2ibm.c

Modified: trunk/SASxport/src/ieee2ibm.c
===================================================================
--- trunk/SASxport/src/ieee2ibm.c	2014-07-18 17:11:52 UTC (rev 1840)
+++ trunk/SASxport/src/ieee2ibm.c	2014-07-18 18:37:51 UTC (rev 1841)
@@ -45,95 +45,111 @@
   static char numeric_NA[8] = {0x2e,0x00,0x00,0x00,0x00,0x00,0x00,0x00};
 
 
-	/*
-	 *  IBM Format.
-	 *  7-bit exponent, base 16.
-	 *  No hidden bits in mantissa (56 bits).
-	 */
-	register int	i;
-	for( i=count-1; i >= 0; i-- )  {
-	  register unsigned int left, right;
-	  register int fix, exp, signbit;
+  /*
+   *  IBM Format.
+   *  7-bit exponent, base 16.
+   *  No hidden bits in mantissa (56 bits).
+   */
+  register int	i;
+  for( i=count-1; i >= 0; i-- )
+    {
+      register unsigned int left, right;
+      register int fix, exp, signbit;
 
-		left  = (in[0]<<24) | (in[1]<<16) | (in[2]<<8) | in[3];
-		right = (in[4]<<24) | (in[5]<<16) | (in[6]<<8) | in[7];
-		in += 8;
+      left  = ( (unsigned int) in[0]<<24) |
+	      (	(unsigned int) in[1]<<16) |
+	      ( (unsigned int) in[2]<<8 ) |
+	      in[3];
+      right = ( (unsigned int) in[4]<<24) |
+              ( (unsigned int) in[5]<<16) |
+              ( (unsigned int) in[6]<<8 ) |
+	      in[7];
+      in += 8;
 
-		exp = ((left >> 20) & 0x7FF);
-		signbit = (left & 0x80000000) >> 24;
+      exp = ((left >> 20) & 0x7FF);
+      signbit = (left & 0x80000000) >> 24;
 
-		if( exp == 0 || exp == 0x7FF )  {
-		        *out++ = 0;		/* IBM zero.  No NAN */
-			*out++ = 0;
-			*out++ = 0;
-			*out++ = 0;
-			*out++ = 0;
-			*out++ = 0;
-			*out++ = 0;
-			*out++ = 0;
-			continue;
-		}
+      if( exp == 0 || exp == 0x7FF )
+	{
+	  *out++ = 0;		/* IBM zero.  No NAN */
+	  *out++ = 0;
+	  *out++ = 0;
+	  *out++ = 0;
+	  *out++ = 0;
+	  *out++ = 0;
+	  *out++ = 0;
+	  *out++ = 0;
+	  continue;
+	}
 
-		left = (left & 0x000FFFFF) | 0x00100000;/* replace "hidden" bit */
+      left = (left & 0x000FFFFF) | 0x00100000;/* replace "hidden" bit */
 
-		exp += 129 - 1023 -1;	/* fudge, to make /4 and %4 work */
-		fix = exp % 4;		/* 2^4 == 16^1;  get fractional exp */
-		exp /= 4;		/* excess 32, base 16 */
-		exp += (64-32+1);	/* excess 64, base 16, plus fudge */
-		if( (exp & ~0xFF) != 0 )  {
-			warning("IBM exponent overflow, generating NA\n");
-			memcpy(out, numeric_NA, 8);
-			out+= 8;
-			continue;
-		}
+      exp += 129 - 1023 -1;	/* fudge, to make /4 and %4 work */
+      fix = exp % 4;		/* 2^4 == 16^1;  get fractional exp */
+      exp /= 4;		/* excess 32, base 16 */
+      exp += (64-32+1);	/* excess 64, base 16, plus fudge */
+      if( (exp & ~0xFF) != 0 )
+	{
+	  warning("IBM exponent overflow, generating NA\n");
+	  memcpy(out, numeric_NA, 8);
+	  out+= 8;
+	  continue;
+	}
 
-		if( fix )  {
-			left = (left<<fix) | (right >> (32-fix));
-			right <<= fix;
-		}
+      if( fix )
+	{
+	  left = ( (unsigned int) left<<fix) | (right >> (32-fix));
+	  right <<= fix;
+	}
 
-		/* if( 0 && signbit )  { */
-		if( 0 )  {
-			/* The IBM actually uses complimented mantissa
-			 * and exponent.
-			 */
-			left  ^= 0xFFFFFFFF;
-			right ^= 0xFFFFFFFF;
-			if( right & 0x80000000 )  {
-				/* There may be a carry */
-				right += 1;
-				if( (right & 0x80000000) == 0 )  {
-					/* There WAS a carry */
-					left += 1;
-				}
-			} else {
-				/* There will be no carry to worry about */
-				right += 1;
-			}
-			left &= 0x00FFFFFF;
-			exp = (~exp) & 0x7F;
+      /* if( 0 && signbit )  { */
+      if( 0 )
+	{
+	  /* The IBM actually uses complimented mantissa
+	   * and exponent.
+	   */
+	  left  ^= 0xFFFFFFFF;
+	  right ^= 0xFFFFFFFF;
+	  if( right & 0x80000000 )
+	    {
+	      /* There may be a carry */
+	      right += 1;
+	      if( (right & 0x80000000) == 0 )
+		{
+		  /* There WAS a carry */
+		  left += 1;
 		}
+	    }
+	  else
+	    {
+	      /* There will be no carry to worry about */
+	      right += 1;
+	    }
+	  left &= 0x00FFFFFF;
+	  exp = (~exp) & 0x7F;
+	}
 
-		/*  Not actually required, but for comparison purposes,
-		 *  normalize the number.  Remove for production speed.
-		 */
-		while( (left & 0x00F00000) == 0 && left != 0 )  {
-			if( signbit && exp <= 0x41 )  break;
+      /*  Not actually required, but for comparison purposes,
+       *  normalize the number.  Remove for production speed.
+       */
+      while( (left & 0x00F00000) == 0 && left != 0 )
+	{
+	  if( signbit && exp <= 0x41 )  break;
 
-			left = (left << 4) | (right >> (32-4));
-			right <<= 4;
-			if(signbit)  exp--;
-			else exp++;
-		}
+	  left = ( (unsigned int) left << 4) | (right >> (32-4));
+	  right <<= 4;
+	  if(signbit)  exp--;
+	  else exp++;
+	}
 
-		*out++ = signbit | exp;
-		*out++ = left>>16;
-		*out++ = left>>8;
-		*out++ = left;
-		*out++ = right>>24;
-		*out++ = right>>16;
-		*out++ = right>>8;
-		*out++ = right;
-	}
-	return;
+      *out++ = signbit | exp;
+      *out++ = left>>16;
+      *out++ = left>>8;
+      *out++ = left;
+      *out++ = right>>24;
+      *out++ = right>>16;
+      *out++ = right>>8;
+      *out++ = right;
+    }
+  return;
 }

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