From e6fc1a92a913e9d865178687e547790f38c3c921 Mon Sep 17 00:00:00 2001
From: Landon Curt Noll <github-mail@asthe.com>
Date: Mon, 28 Nov 2022 15:13:16 -0800
Subject: [PATCH] Improve file position handling on Big Engian machines

Added swap_HALFs(dest, src, len) function to byteswap.c.

Calc can now handle Big Engian file position sizes that are a
multiple of BASEB bits in length.  Before handle Big Engian file
positions could only be 32 and 64 bits in length.  This will allow,
for example, a Big Engian file position size of 128 (assuming that
128/BASEB is is an integer).
---
 CHANGES    |  8 ++++++++
 byteswap.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++--
 fposval.c  |  8 ++++++--
 zmath.h    |  1 +
 4 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/CHANGES b/CHANGES
index 81b0245..2334577 100644
--- a/CHANGES
+++ b/CHANGES
@@ -27,6 +27,14 @@ The following are the changes from calc version 2.14.1.2 to date:
     to CALC_HAVE_FGETSETPOS_H.  The make install and the olduninstall
     rules remove the any old have_fpos.h that was previously installed.
 
+    Added swap_HALFs(dest, src, len) function to byteswap.c.
+
+    Calc can now handle Big Engian file position sizes that are a
+    multiple of BASEB bits in length.  Before handle Big Engian file
+    positions could only be 32 and 64 bits in length.  This will allow,
+    for example, a Big Engian file position size of 128 (assuming that
+    128/BASEB is is an integer).
+
 
 The following are the changes from calc version 2.14.1.1 to 2.14.1.1:
 
diff --git a/byteswap.c b/byteswap.c
index c1c5e55..33811b5 100644
--- a/byteswap.c
+++ b/byteswap.c
@@ -40,7 +40,7 @@
  *	dest	- pointer to where the swapped src will be put or
  *		  NULL to allocate the storage
  *	src	- pointer to a HALF array to swap
- *	len	- length of the src HALF array
+ *	len	- length of the src HALF array in HALFs
  *
  * returns:
  *	pointer to where the swapped src has been put
@@ -276,7 +276,7 @@ swap_b8_in_COMPLEX(COMPLEX *dest, COMPLEX *src, BOOL all)
  *	dest	- pointer to where the swapped src will be put or
  *		  NULL to allocate the storage
  *	src	- pointer to a HALF array to swap
- *	len	- length of the src HALF array
+ *	len	- length of the src HALF array in HALFs
  *
  * returns:
  *	pointer to where the swapped src has been put
@@ -309,6 +309,50 @@ swap_b16_in_HALFs(HALF *dest, HALF *src, LEN len)
 }
 
 
+/*
+ * swap_HALFs - swap HALFs in an array of HALFs
+ *
+ * given:
+ *	dest	- pointer to where the swapped src will be put or
+ *		  NULL to allocate the storage
+ *	src	- pointer to a HALF array to swap
+ *	len	- length of the src HALF array in HALFs
+ *
+ * returns:
+ *	pointer to where the swapped src has been put
+ */
+HALF *
+swap_HALFs(HALF *dest, HALF *src, LEN len)
+{
+	HALF *s;	/* src swap pointer */
+	HALF *d;	/* dest swap pointer */
+	HALF *ret;
+	LEN i;
+
+	/*
+	 * allocate storage if needed
+	 */
+	if (dest == NULL) {
+		dest = alloc(len);
+	}
+	ret = dest;
+
+	/*
+	 * swap HALFs in the array
+	 */
+	s = src;
+	d = &dest[len-1];
+	for (i=0; i < len; ++i, --d, ++s) {
+		*d = *s;
+	}
+
+	/*
+	 * return the result
+	 */
+	return ret;
+}
+
+
 /*
  * swap_b16_in_ZVALUE - swap 16 bits in a ZVALUE
  *
diff --git a/fposval.c b/fposval.c
index 04d3042..d851f53 100644
--- a/fposval.c
+++ b/fposval.c
@@ -96,7 +96,7 @@ main(int UNUSED(argc), char **argv)
 	/*
 	 * print the file position information
 	 */
-#if defined(HAVE_FPOS_POS)
+#if defined(HAVE_FPOS_POS) && defined(FPOS_POS_BITS)
 	fileposlen = FPOS_POS_BITS;
 #else /* ! HAVE_FPOS_POS */
 # if defined(FPOS_BITS)
@@ -119,8 +119,12 @@ main(int UNUSED(argc), char **argv)
 	} else if (fileposlen == 32) {
 		printf("#define SWAP_HALF_IN_FILEPOS(dest, src)\t\t%s\n",
 		    "SWAP_HALF_IN_B32(dest, src)");
+	} else if (fileposlen%BASEB == 0) {
+		printf("#define SWAP_HALF_IN_FILEPOS(dest, src)\t\t"
+		       "swap_HALFs((HALF *)dest, (HALF *)src, (LEN)%d)\n",
+		       fileposlen/BASEB);
 	} else {
-		fprintf(stderr, "%s: unexpected FILEPOS bit size: %d\n",
+		fprintf(stderr, "%s: unexpected BIG_ENDIAN FILEPOS bit size: %d\n",
 		    program, fileposlen);
 		exit(1);
 	}
diff --git a/zmath.h b/zmath.h
index d3e0295..e2fdcfb 100644
--- a/zmath.h
+++ b/zmath.h
@@ -643,6 +643,7 @@ E_FUNC void math_error(char *, ...) \
 E_FUNC HALF *swap_b8_in_HALFs(HALF *dest, HALF *src, LEN len);
 E_FUNC ZVALUE *swap_b8_in_ZVALUE(ZVALUE *dest, ZVALUE *src, BOOL all);
 E_FUNC HALF *swap_b16_in_HALFs(HALF *dest, HALF *src, LEN len);
+E_FUNC HALF *swap_HALFs(HALF *dest, HALF *src, LEN len);
 E_FUNC ZVALUE *swap_b16_in_ZVALUE(ZVALUE *dest, ZVALUE *src, BOOL all);
 E_FUNC ZVALUE *swap_HALF_in_ZVALUE(ZVALUE *dest, ZVALUE *src, BOOL all);