From sources-request at octave dot org Tue Jun  1 03:34:23 2004
Subject: VAX<-->IEEE 32bit float conversion
From: Wolfgang Westphal <wolfgang dot westphal at ph dot tum dot de>
To: sources at octave dot org
Date: Tue, 1 Jun 2004 10:32:48 +0200


--Boundary-00=_w8DvApaxnh+X0o2
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

Hi!

I had to read some data files containing float values in VAX notation, 
so I've implemented the conversion for 32bit VAX floats to IEEE little 
endian. AFAIK for the 32bit case there's no difference between "VAX-D" 
and "VAX-G", so the conversion is identical in both cases.

The attached patch is tested in octave 2.1.50 as well as octave 2.1.57, 
and worksforme.

Regards,
Wolfgang Westphal

--Boundary-00=_w8DvApaxnh+X0o2
Content-Type: text/x-diff;
  charset="iso-8859-1";
  name="vaxieee.diff"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
	filename="vaxieee.diff"

--- liboctave/data-conv.cc	2002-04-10 02:39:51.000000000 +0200
+++ liboctave/data-conv.cc	2004-05-31 13:10:14.000000000 +0200
 at @ -277,15 +277,26 @@
 }
 
 static void
-VAX_D_float_to_IEEE_little_float (float * /* d */, int /* len */)
+VAX_D_float_to_IEEE_little_float (float * d, int len)
 {
-  gripe_data_conversion ("VAX D float", "IEEE little endian format");
+  for (int i=0;i<len;i++) {
+    char* c = (char*)(&d[i]);
+    swap_bytes(c, 0, 2);
+    swap_bytes(c, 1, 3);
+    c[3]--;
+  }
 }
 
 static void
-VAX_G_float_to_IEEE_little_float (float * /* d */, int /* len */)
-{
-  gripe_data_conversion ("VAX G float", "IEEE little endian format");
+VAX_G_float_to_IEEE_little_float (float * d , int len )
+{
+  char* c;
+  for (int i=0;i<len;i++) {
+    c = (char*)(&d[i]);
+    swap_bytes(c, 0, 2);
+    swap_bytes(c, 1, 3);
+    c[3]--;
+  }
 }
 
 static void
 at @ -367,9 +378,14 @@
 }
 
 static void
-IEEE_little_float_to_VAX_D_float (float * /* d */, int /* len */)
+IEEE_little_float_to_VAX_D_float (float * d , int len)
 {
-  gripe_data_conversion ("IEEE little endian", "VAX D");
+  for (int i=0;i<len;i++) {
+    char* c = (char*)(&d[i]);
+    c[3]++;
+    swap_bytes(c, 0, 2);
+    swap_bytes(c, 1, 3);
+  }
 }
 
 static void
 at @ -415,9 +431,14 @@
 }
 
 static void
-IEEE_little_float_to_VAX_G_float (float * /* d */, int /* len */)
+IEEE_little_float_to_VAX_G_float (float * d , int len)
 {
-  gripe_data_conversion ("IEEE little endian", "VAX G");
+  for (int i=0;i<len;i++) {
+    char* c = (char*)(&d[i]);
+    c[3]++;
+    swap_bytes(c, 0, 2);
+    swap_bytes(c, 1, 3);
+  }
 }
 
 static void

--Boundary-00=_w8DvApaxnh+X0o2--