From 255f0d4b2a4758f9b31ca280698b30c4bbd1fec2 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 30 Jun 2019 22:33:54 -0400
Subject: [PATCH] Corrects MULS timing.

---
 .../68000/Implementation/68000Implementation.hpp      | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/Processors/68000/Implementation/68000Implementation.hpp b/Processors/68000/Implementation/68000Implementation.hpp
index 03c67335e..0b2f3aa55 100644
--- a/Processors/68000/Implementation/68000Implementation.hpp
+++ b/Processors/68000/Implementation/68000Implementation.hpp
@@ -945,18 +945,19 @@ template <class T, bool dtack_is_implicit, bool signal_will_perform> void Proces
 									zero_result_ = active_program_->destination->full;
 									negative_flag_ = zero_result_ & 0x80000000;
 
+									// Find the number of 01 or 10 pairs in the 17-bit number
+									// formed by the source value with a 0 suffix.
 									// TODO: optimise the below?
 									int number_of_pairs = 0;
 									int source = active_program_->source->halves.low.full;
-									int bit = 0;
-									while(source | bit) {
-										number_of_pairs += (bit ^ source) & 1;
-										bit = source & 1;
+									source = (source ^ (source << 1)) & 0xffff;
+									while(source) {
+										if(source&1) ++number_of_pairs;
 										source >>= 1;
 									}
 
 									// Time taken = 38 cycles + 2 cycles per 1 in the source.
-									set_next_microcycle_length(HalfCycles(4 * number_of_pairs + 38*2));
+									set_next_microcycle_length(HalfCycles(4 * number_of_pairs + 34*2));
 								} break;
 
 								/*