fix #13, allow size to be 65535 (uint16_t) (#14)

- fix #13, allow size to be 65535 (uint16_t)
- add patch for possible interpolation under/overflows. 
- add multi type **multiMapCache<T1, T2>** as it was missing.
- update readme.md
- update GitHub actions
- minor edits

Author: RobTillaart

.github/workflows/arduino-lint.yml

@@ -6,8 +6,8 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 5
     steps:
-      - uses: actions/checkout@v4
-      - uses: arduino/arduino-lint-action@v1
+      - uses: actions/checkout@v6
+      - uses: arduino/arduino-lint-action@v2
         with:
           library-manager: update
           compliance: strict

.github/workflows/arduino_test_runner.yml

@@ -6,9 +6,8 @@ jobs:
   runTest:
     runs-on: ubuntu-latest
     timeout-minutes: 20
-
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: 2.6

.github/workflows/jsoncheck.yml

@@ -5,13 +5,15 @@ on:
     paths:
       - '**.json'
   pull_request:
+    paths:
+      - '**.json'
 
 jobs:
   test:
     runs-on: ubuntu-latest
     timeout-minutes: 5
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: json-syntax-check
         uses: limitusus/json-syntax-check@v2
         with:

CHANGELOG.md

@@ -6,6 +6,16 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.3.0] - 2026-02-23
+- fix #13, allow size to be 65535 (uint16_t)
+- add patch for possible interpolation under/overflows. 
+- add multi type **multiMapCache<T1, T2>** as it was missing.
+- update readme.md
+- update GitHub actions
+- minor edits
+
+----
+
 ## [0.2.1] - 2025-07-17
 - update readme.md
 - add multiMap_demo.ino

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2011-2025 Rob Tillaart
+Copyright (c) 2011-2026 Rob Tillaart
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

MultiMap.h

@@ -2,15 +2,15 @@
 //
 //    FILE: MultiMap.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.2.1
+// VERSION: 0.3.0
 //    DATE: 2011-01-26
 // PURPOSE: Arduino library for fast non-linear mapping or interpolation of values
 //     URL: https://github.com/RobTillaart/MultiMap
 //     URL: http://playground.arduino.cc/Main/MultiMap
 
 
 
-#define MULTIMAP_LIB_VERSION                (F("0.2.1"))
+#define MULTIMAP_LIB_VERSION                (F("0.3.0"))
 
 
 #include "Arduino.h"
@@ -22,21 +22,23 @@
 //
 //  note: the in array must have increasing values
 template<typename T>
-T multiMap(T value, T* _in, T* _out, uint8_t size)
+T multiMap(T value, T* _in, T* _out, uint16_t size)
 {
   //  output is constrained to out array
   if (value <= _in[0]) return _out[0];
   if (value >= _in[size-1]) return _out[size-1];
 
   //  search right interval
-  uint8_t pos = 1;  // _in[0] already tested
+  uint16_t pos = 1;  // _in[0] already tested
   while(value > _in[pos]) pos++;
 
   //  this will handle all exact "points" in the _in array
   if (value == _in[pos]) return _out[pos];
 
   //  interpolate in the right segment for the rest
   return (value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1]) + _out[pos-1];
+  //  if interpolation overflows use this line
+  //  return T(float(value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1])) + _out[pos-1];
 }
 
 
@@ -49,7 +51,7 @@ T multiMap(T value, T* _in, T* _out, uint8_t size)
 //     e.g.  2 2 2 2 2 3 3 3 3 5 5 5 5 5 5 8 8 8 8 5 5 5 5 5
 //  implements a minimal cache of the lastValue.
 template<typename T>
-T multiMapCache(T value, T* _in, T* _out, uint8_t size)
+T multiMapCache(T value, T* _in, T* _out, uint16_t size)
 {
   static T lastValue = -1;  //  possible bug for 1st call
   static T cache = -1;
@@ -72,7 +74,7 @@ T multiMapCache(T value, T* _in, T* _out, uint8_t size)
   else
   {
     //  search right interval; index 0 _in[0] already tested
-    uint8_t pos = 1;
+    uint16_t pos = 1;
     while(value > _in[pos]) pos++;
 
     //  this will handle all exact "points" in the _in array
@@ -84,6 +86,8 @@ T multiMapCache(T value, T* _in, T* _out, uint8_t size)
     {
       //  interpolate in the right segment for the rest
       cache = (value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1]) + _out[pos-1];
+      //  if interpolation overflows use this line
+      //  cache = T(float(value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1])) + _out[pos-1];
     }
   }
   return cache;
@@ -99,7 +103,7 @@ T multiMapCache(T value, T* _in, T* _out, uint8_t size)
 //
 //  note: the in array must have increasing values
 template<typename T>
-T multiMapBS(T value, T* _in, T* _out, uint8_t size)
+T multiMapBS(T value, T* _in, T* _out, uint16_t size)
 {
   //  output is constrained to out array
   if (value <= _in[0]) return _out[0];
@@ -110,12 +114,14 @@ T multiMapBS(T value, T* _in, T* _out, uint8_t size)
   uint16_t upper = size - 1;
   while (lower < upper - 1)
   {
-    uint8_t mid = (lower + upper) / 2;
+    uint16_t mid = (lower + upper) / 2;
     if (value >= _in[mid]) lower = mid;
     else upper = mid;
   }
-
+  //  interpolate in the right segment for the rest
   return (value - _in[lower]) * (_out[upper] - _out[lower]) / (_in[upper] - _in[lower]) + _out[lower];
+  //  if interpolation overflows use this line
+  //  return T(float(value - _in[lower]) * (_out[upper] - _out[lower]) / (_in[upper] - _in[lower])) + _out[lower];
 }
 
 
@@ -125,7 +131,7 @@ T multiMapBS(T value, T* _in, T* _out, uint8_t size)
 //
 //  note: the in array must have increasing values
 template<typename T1, typename T2>
-T2 multiMap(T1 value, T1* _in, T2* _out, uint8_t size)
+T2 multiMap(T1 value, T1* _in, T2* _out, uint16_t size)
 {
   //  output is constrained to out array
   if (value <= _in[0]) return _out[0];
@@ -140,6 +146,60 @@ T2 multiMap(T1 value, T1* _in, T2* _out, uint8_t size)
 
   //  interpolate in the right segment for the rest
   return (value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1]) + _out[pos-1];
+  //  if interpolation overflows use this line
+  //  return T2(float(value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1])) + _out[pos-1];
+}
+
+
+////////////////////////////////////////////////////////////////////////
+//
+//  MULTITYPE TYPE MULTIMAP CACHE - LINEAR SEARCH
+//
+//  note: the in array must have increasing values
+//  performance optimized version if inputs do not change often
+//     e.g.  2 2 2 2 2 3 3 3 3 5 5 5 5 5 5 8 8 8 8 5 5 5 5 5
+//  implements a minimal cache of the lastValue.
+template<typename T1, typename T2>
+T2 multiMapCache(T1 value, T1* _in, T2* _out, uint16_t size)
+{
+  static T1 lastValue = -1;  //  possible bug for 1st call
+  static T2 cache = -1;
+
+  if (value == lastValue)
+  {
+    return cache;
+  }
+  lastValue = value;
+
+  //  output is constrained to out array
+  if (value <= _in[0])
+  {
+    cache = _out[0];
+  }
+  else if (value >= _in[size-1])
+  {
+    cache = _out[size-1];
+  }
+  else
+  {
+    //  search right interval; index 0 _in[0] already tested
+    uint16_t pos = 1;
+    while(value > _in[pos]) pos++;
+
+    //  this will handle all exact "points" in the _in array
+    if (value == _in[pos])
+    {
+      cache = _out[pos];
+    }
+    else
+    {
+      //  interpolate in the right segment for the rest
+      cache = (value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1]) + _out[pos-1];
+      //  if interpolation overflows use this line
+      //  return T2(float(value - _in[pos-1]) * (_out[pos] - _out[pos-1]) / (_in[pos] - _in[pos-1])) + _out[pos-1];
+    }
+  }
+  return cache;
 }
 
 
@@ -151,7 +211,7 @@ T2 multiMap(T1 value, T1* _in, T2* _out, uint8_t size)
 //
 //  note: the in array must have increasing values
 template<typename T1, typename T2>
-T2 multiMapBS(T1 value, T1* _in, T2* _out, uint8_t size)
+T2 multiMapBS(T1 value, T1* _in, T2* _out, uint16_t size)
 {
   //  output is constrained to out array
   if (value <= _in[0]) return _out[0];
@@ -166,8 +226,10 @@ T2 multiMapBS(T1 value, T1* _in, T2* _out, uint8_t size)
     if (value >= _in[mid]) lower = mid;
     else upper = mid;
   }
-
+  //  interpolate in the right segment for the rest
   return (value - _in[lower]) * (_out[upper] - _out[lower]) / (_in[upper] - _in[lower]) + _out[lower];
+  //  if interpolation overflows use this line
+  //  return T2(float(value - _in[lower]) * (_out[upper] - _out[lower]) / (_in[upper] - _in[lower])) + _out[lower];
 }