From: lkcl <lkcl@web>
Date: Thu, 29 Jul 2021 04:32:58 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: DRAFT_SVP64_0_1~578
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=4e1af6bc18353ecf044545325024b5369ec50cae;p=libreriscv.git

---

diff --git a/openpower/sv/svp64/appendix.mdwn b/openpower/sv/svp64/appendix.mdwn
index 395b732f8..65c089f07 100644
--- a/openpower/sv/svp64/appendix.mdwn
+++ b/openpower/sv/svp64/appendix.mdwn
@@ -735,54 +735,31 @@ For modes:
 
 # Proposed Parallel-reduction algorithm
 
-this is actually prefix-sum (Pascal's Triangle)
-
 ```
 /// reference implementation of proposed SimpleV reduction semantics.
 ///
-/// `temp_pred` is a non-user-visible register that can be stored in some
-/// SPR if the reduction is interrupted, or we can just restart the
-reduction
-/// from the beginning since it will produce the same results.
+/// `temp_pred` is a user-visible Vector Condition register 
 ///
 /// all input arrays have length `vl`
-pub fn reduce(
-    vl: usize,
-    input_vec: &[f32],
-    temp_vec: &mut [f32],
-    input_pred: &[bool],
-    temp_pred: &mut [bool],
-) -> f32 {
-    assert_eq!(input_vec.len(), vl);
-    assert_eq!(temp_vec.len(), vl);
-    assert_eq!(input_pred.len(), vl);
-    assert_eq!(temp_pred.len(), vl);
-    for i in 0..vl {
+pub fn reduce(  vl,  input_vec, temp_vec, input_pred, temp_pred,):
+    for i in 0..vl
         temp_pred[i] = input_pred[i];
-        if temp_pred[i] {
-            temp_vec[i] = input_vec[i];
-        }
-    }
-    let mut step = 1;
-    while step < vl {
+        if temp_pred[i]
+            temp_vec[i] = input_vec[i]
+    mut step = 1;
+    while step < vl
         step *= 2;
-        for i in (0..vl).step_by(step) {
-            let other = i + step / 2;
-            let other_pred = other < vl && temp_pred[other];
-            if temp_pred[i] && other_pred {
+        for i in (0..vl).step_by(step)
+            other = i + step / 2;
+            other_pred = other < vl && temp_pred[other];
+            if temp_pred[i] && other_pred
                 // reduction operation -- we still use this algorithm even
                 // if the reduction operation isn't associative or
                 // commutative.
-                //
-                // `f32` addition is used as the reduction operation
-                // for ease of exposition.
                 temp_vec[i] += temp_vec[other];
-            } else if other_pred {
+            else if other_pred
                 temp_vec[i] = temp_vec[other];
-            }
             temp_pred[i] |= other_pred;
-        }
-    }
     if vl != 0 && temp_pred[0] {
         // return the result
         temp_vec[0]