From 798b2b1435fd2e6f4b51c55af219ff01c685db1d Mon Sep 17 00:00:00 2001
From: erdgeist <de@gsmk.de>
Date: Mon, 6 Oct 2014 17:25:51 +0200
Subject: Clean up table generator

---
 generate_table.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 67 insertions(+), 9 deletions(-)

diff --git a/generate_table.c b/generate_table.c
index c7a9d0c..9fd05bc 100644
--- a/generate_table.c
+++ b/generate_table.c
@@ -6,6 +6,59 @@
 // s( 1) n(-4) off( 0)   x =       ( x <<  4 )
 // s( 1) n( 8) off(-1)   x = - x + ( x <<  8 )
 
+typedef enum { use_2pn, use_1_2pn, use_2pm_2pn, use_1_2pm_2pn } tr_flag;
+typedef struct {
+  double factor;
+  int     n;
+  int     m;
+  int     nsign;
+  tr_flag flag;
+} table_record;
+
+static int g_records;
+static table_record g_tr[8192];
+
+static int compare_record( const void *a, const void *b ) {
+  if( ((table_record*)a)->factor > ((table_record*)b)->factor )
+    return 1;
+  if( ((table_record*)a)->factor < ((table_record*)b)->factor )
+    return -1;
+  return 0;
+}
+
+static void add_record( double v, int n, int nsign, int m, tr_flag flag )
+{
+    g_tr[g_records].factor = v;
+    g_tr[g_records].n      = n;
+    g_tr[g_records].m      = m;
+    g_tr[g_records].nsign  = nsign;
+    g_tr[g_records].flag   = flag;
+    ++g_records;
+}
+
+static void dump_record( int record )
+{
+  if( record >= g_records ) return; // should warn?
+  double factor = g_tr[record].factor;
+  int n         = g_tr[record].n;
+  int m         = g_tr[record].m;
+  int nsign     = g_tr[record].nsign;
+  tr_flag flag  = g_tr[record].flag;
+
+  switch( flag ) {
+    case use_2pn:
+      printf( "%0+25.21lf x =   x %s %2d\n", factor, n>=0?"<<":">>", (int)abs(n) );
+      break;
+    case use_1_2pn:
+      printf( "%0+25.21lf x%s=   x %s %2d\n", factor, nsign==-1?"-":"+", n>=0?"<<":">>", (int)abs(n) );
+      break;
+    case use_2pm_2pn:
+    case use_1_2pm_2pn:
+      printf( "%0+25.21lf x%s= ( x %s %2d ) %s ( x %s %2d )\n", factor, flag==use_2pm_2pn?" ":"-", m>=0?"<<":">>", (int)abs(m), nsign==-1?"-":"+", n>=0?"<<":">>", (int)abs(n));
+      break;
+  }
+}
+
 int main() {
   int n, m, nsign;
 
@@ -14,21 +67,26 @@ int main() {
     for ( nsign=-1; nsign<=1; nsign+=2 )
     {
       // The one term only case
-      double v = (double)nsign * pow( 2.f, (double)n );
-      if( v > 0.f )
-          printf( "%0+25.21lf %08X x =             %s ( x %s %2d )%s\n", log(v), abs((int)(67108864.f*log(v))), nsign==-1?"-":" ", n>=0?"<<":">>", (int)abs(n), " !RECOMMENDED!" );
+      double v = (double)nsign * pow( 2., (double)n );
+      if( v > 0.0 )
+          add_record( log(v), n, nsign, m, use_2pn );
 
       // Loop over second term
       for (m=-31; m<=31; ++m )
       {
-        double v = pow( 2.f, (double)m ) + (double)nsign * pow( 2.f, (double)n );
-        if( v > 0.f ) {
-          printf( "%0+25.21lf %08X x = ( x %s %2d ) %s ( x %s %2d )%s\n", log(v), abs((int)(67108864.f*log(v))), m>=0?"<<":">>", (int)abs(m), nsign==-1?"-":"+", n>=0?"<<":">>", (int)abs(n), n*m?"":" !RECOMMENDED!" );
-          if( v < 1.f )
-              printf( "%0+25.21lf %08X x-= ( x %s %2d ) %s ( x %s %2d )\n", log(1.0f - v), abs((int)(67108864.f*log(1.0f - v))), m>=0?"<<":">>", (int)abs(m), nsign==-1?"-":"+", n>=0?"<<":">>", (int)abs(n) );
-        }
+        double v = pow( 2.0, (double)m ) + (double)nsign * pow( 2., (double)n );
+        if( v <= 0.0 )
+          continue;
+        add_record( log(v), n, nsign, m, m ? use_2pm_2pn : use_1_2pn );
+        if( v < 1.0 )
+          add_record( log(1.0 - v), n, nsign, m, use_1_2pm_2pn );
       }
     }
 
+  qsort( g_tr, g_records, sizeof(*g_tr), compare_record );
+
+  for (n=0; n<g_records; ++n )
+    dump_record(n);
+
   return 0;
 }
-- 
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