From fa2ced8062514f1e53b227989667e298cd8795af Mon Sep 17 00:00:00 2001
From: tslil clingman <tslil@posteo.de>
Date: Sat, 22 Oct 2022 20:19:27 +0200
Subject: let lsb inform index block allocation between hands

---
 srchr/src/config.rs |  6 +++---
 srchr/src/layout.rs | 26 +++++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 4 deletions(-)

(limited to 'srchr')

diff --git a/srchr/src/config.rs b/srchr/src/config.rs
index 60cd80c..f89aa18 100644
--- a/srchr/src/config.rs
+++ b/srchr/src/config.rs
@@ -16,13 +16,13 @@ U V W X Y  Z . , / '
 // Tournament parameters
 pub const NUM_CONTESTANTS: usize = 256;
 pub const NUM_PERSIST: usize = 8;
-pub const MAX_NUM_TRANSPOSITIONS: usize = 15;
+pub const MAX_NUM_TRANSPOSITIONS: usize = 6;
 
 // Fitness parameters
 pub const STANDARD_DSFB_WEIGHT: f32 = 1.0 / 3.0;
 pub const INDEX_DSFB_WEIGHT: f32 = 1.0 / 3.0;
 
-pub const MIN_INDEX_USAGE_PERCENT: f32 = 0.10;
+pub const MIN_INDEX_USAGE_PERCENT: f32 = 0.12;
 pub fn index_usage_fitness(index_perc: f32) -> f32 {
     if index_perc < MIN_INDEX_USAGE_PERCENT {
         MIN_INDEX_USAGE_PERCENT - index_perc
@@ -31,7 +31,7 @@ pub fn index_usage_fitness(index_perc: f32) -> f32 {
     }
 }
 
-pub const MAX_PINKY_USAGE_PERCENT: f32 = 0.085;
+pub const MAX_PINKY_USAGE_PERCENT: f32 = 0.092;
 pub fn pinky_col_penalty(lesser_perc: f32, greater_perc: f32) -> f32 {
     if greater_perc > MAX_PINKY_USAGE_PERCENT {
         if lesser_perc > MAX_PINKY_USAGE_PERCENT {
diff --git a/srchr/src/layout.rs b/srchr/src/layout.rs
index 8f8b03a..e6ac862 100644
--- a/srchr/src/layout.rs
+++ b/srchr/src/layout.rs
@@ -167,7 +167,31 @@ impl Layout {
         }
 
         let w_index_columns = weight_function(&pl.index_columns, corpus);
-        let (left_ind, right_ind) = if balance >= 0.0 { (0, 1) } else { (1, 0) };
+        // Choose index order to minimise LSB (middle-index only) even though we
+        // don't directly optimise for this parameter
+        let mut lsbs = [0.0; 2];
+        for option in [0, 1] {
+            for left in [true, false] {
+                let mind = if left { 2 } else { 7 };
+                let side = if left { option } else { 1 - option };
+                let m1 = keys[mind + 10 * 0] as u8;
+                let m2 = keys[mind + 10 * 1] as u8;
+                let m3 = keys[mind + 10 * 2] as u8;
+                let i1 = w_index_columns[side].0[3];
+                let i2 = w_index_columns[side].0[4];
+                let i3 = w_index_columns[side].0[5];
+                lsbs[option] += corpus.get_bigram_perc(m1, i1)
+                    + corpus.get_bigram_perc(m1, i2)
+                    + corpus.get_bigram_perc(m1, i3)
+                    + corpus.get_bigram_perc(m2, i1)
+                    + corpus.get_bigram_perc(m2, i2)
+                    + corpus.get_bigram_perc(m2, i3)
+                    + corpus.get_bigram_perc(m3, i1)
+                    + corpus.get_bigram_perc(m3, i2)
+                    + corpus.get_bigram_perc(m3, i3);
+            }
+        }
+        let (left_ind, right_ind) = if lsbs[0] < lsbs[1] { (0, 1) } else { (1, 0) };
         for j in 0..3 {
             keys[3 + j * ROW_LENGTH] = w_index_columns[left_ind].0[j] as char;
             keys[6 + j * ROW_LENGTH] = w_index_columns[right_ind].0[j] as char;
-- 
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