From 431a35c2cd744e9c53cc401928f193aae6fbb109 Mon Sep 17 00:00:00 2001
From: "Paul A. Clarke" <pc@us.ibm.com>
Date: Mon, 11 May 2020 15:52:56 -0500
Subject: [PATCH] Clarify content regarding operators

- Explicitly mention that there are no default conversions.
- Clarify that binary operations are on like types.
- Clarify requirements for the ternary operator and add an example.

Asserting that the clarified content is clear enough,
Fixes #11.

Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
---
 Intrinsics_Reference/ch_biendian.xml | 38 +++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/Intrinsics_Reference/ch_biendian.xml b/Intrinsics_Reference/ch_biendian.xml
index b18f13f..c446aec 100644
--- a/Intrinsics_Reference/ch_biendian.xml
+++ b/Intrinsics_Reference/ch_biendian.xml
@@ -187,7 +187,8 @@ vector double g = (vector double) { 3.5, -24.6 };</programlisting>
     <para>
       One vector type may be cast to another vector type without
       restriction.  Such a cast is simply a reinterpretation of the
-      bits, and does not change the data.
+      bits, and does not change the data. There are no default
+      conversions for vector types.
     </para>
     <para>
       Compilers are expected to recognize and optimize multiple
@@ -494,12 +495,14 @@ register vector double vd = vec_splats(*double_ptr);</programlisting>
       valid for pointers to vector types.
     </para>
     <para>
-      The traditional C/C++ operators are defined on vector types
-      for unary and binary <code>+</code>,
-      unary and binary &#8211;, binary <code>*</code>, binary
-      <code>%</code>, and binary <code>/</code> as well as the unary
-      and binary shift, logical and comparison operators, and the
-      ternary <code>?:</code> operator.  These operators perform their
+      The traditional C/C++ unary operators (<code>+</code>
+      <code>-</code>, and <code>~</code>), are defined on vector types.
+      The traditional C/C++ binary operators (<code>+</code>,
+      <code>-</code>, <code>*</code>, <code>%</code>, <code>/</code>,
+      shift, logical, and comparison) and the ternary operator
+      (<code>?:</code>)
+      are defined on like vector types.
+      Other than <code>?:</code>, these operators perform their
       operations "elementwise" on the base elements of the operands,
       as follows.
     </para>
@@ -532,6 +535,27 @@ a = a + b;</programlisting>
     </para>
     <programlisting>vector signed int a, b;
 a = vec_add (a, b);</programlisting>
+    <para>
+      For the ternary operator (<code>?:</code>), the first operand must
+      be an integral type, used to select between the second and third
+      operands which must be of the same vector type.
+      The result of the ternary operator will also have that type.
+      For example,
+    <programlisting>
+int test_value;
+vector signed int a, b, r;
+r = test_value ? a : b;
+    </programlisting>
+      produces the same result as
+    <programlisting>
+int test_value;
+vector signed int a, b, r;
+if (test_value)
+  r = a;
+else
+  r = b;
+    </programlisting>
+    </para>
     <para>
       Further, the array reference operator may be applied to vector
       data types, yielding an l-value corresponding to the specified
-- 
2.34.1