From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Sun, 17 Apr 2022 16:44:39 +0000 (+0100)
Subject: whitespace
X-Git-Tag: opf_rfc_ls005_v1~2753
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=04c401dda2eb751b1dfe1d614230e2d1790c581b;p=libreriscv.git

whitespace
---

diff --git a/openpower/sv/bitmanip/appendix.mdwn b/openpower/sv/bitmanip/appendix.mdwn
index edf85fea0..e79894947 100644
--- a/openpower/sv/bitmanip/appendix.mdwn
+++ b/openpower/sv/bitmanip/appendix.mdwn
@@ -42,28 +42,33 @@ The key loop may be implemented with a 4-in, 2-out mul-twin-add
 ```
 On Sat, Apr 16, 2022, 22:06 Jacob Lifshay <programmerjake@gmail.com> wrote:
 and a mrsubcarry (the one actually needed by bigint division):
-# for big_c - big_a * word_b
-result <- RC + ~(RA * RB) + CARRY # this expression is wrong, needs further thought
-CARRY <- HIGH_HALF(result)
-RT <- LOW_HALF(result)
-
-turns out, after some checking with 4-bit words, afaict the correct algorithm for mrsubcarry is:
-# for big_c - big_a * word_b
-result <- RC + ~(RA * RB) + CARRY
-result_high <- HIGH_HALF(result)
-if CARRY <= 1 then # unsigned comparison
-    result_high <- result_high + 1
-end
-CARRY <- result_high
-RT <- LOW_HALF(result)
+
+    # for big_c - big_a * word_b
+    result <- RC + ~(RA * RB) + CARRY # wrong, needs further thought
+    CARRY <- HIGH_HALF(result)
+    RT <- LOW_HALF(result)
+
+turns out, after some checking with 4-bit words, afaict the correct
+algorithm for mrsubcarry is:
+
+    # for big_c - big_a * word_b
+    result <- RC + ~(RA * RB) + CARRY
+    result_high <- HIGH_HALF(result)
+    if CARRY <= 1 then # unsigned comparison
+        result_high <- result_high + 1
+    end
+    CARRY <- result_high
+    RT <- LOW_HALF(result)
 
 afaict, that'll make the following algorithm work:
 
-so the inner loop in the bigint division algorithm would end up being (assuming n, d, and q all fit in registers):
-li r3, 1 # carry in for subtraction
-mtspr CARRY, r3 # init carry spr
-setvl loop_count
-sv.mrsubcarry rn.v, rd.v, rq.s, rn.v
+so the inner loop in the bigint division algorithm would end up being
+(assuming n, d, and q all fit in registers):
+
+    li r3, 1 # carry in for subtraction
+    mtspr CARRY, r3 # init carry spr
+    setvl loop_count
+    sv.mrsubcarry rn.v, rd.v, rq.s, rn.v
 ```
 
 This algorithm may be morphed into a pair of Vector operations by temporary