Fix #13, add wrapper functions (#14)

- Fix #13, add wrapper functions - write16/24/32, write(array, size) - improved timing measurement in FastShiftOut_test.ino - update readme.md - minor edits
RobTillaart · Jul 23, 2024 · 9ac57a7 · 9ac57a7
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,9 +6,15 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
-## [0.3.2] - 2023-10-31
+## [0.3.3] - 2024-07-23
+- Fix #13, add wrapper functions
+  - write16/24/32, write(array, size)
+- improved timing measurement in FastShiftOut_test.ino
 - update readme.md
+- minor edits
 
+## [0.3.2] - 2023-10-31
+- update readme.md
 
 ## [0.3.1] - 2023-02-20
 - update readme.md

diff --git a/FastShiftOut.cpp b/FastShiftOut.cpp
@@ -47,28 +47,113 @@ size_t FastShiftOut::write(uint8_t data)
 }
 
 
-/* experimental
-size_t write(const uint8_t \*buffer, size_t size)
+//  EXPERIMENTAL 0.3.3
+size_t FastShiftOut::write16(uint16_t data)
+{
+  if (_bitOrder == LSBFIRST)
+  {
+    writeLSBFIRST(data & 0xFF);
+    writeLSBFIRST(data >> 8);
+  }
+  else
+  {
+    writeMSBFIRST(data >> 8);
+    writeMSBFIRST(data & 0xFF);
+  }
+  return 2;
+}
+
+
+//  EXPERIMENTAL 0.3.3
+size_t FastShiftOut::write24(uint32_t data)
+{
+  if (_bitOrder == LSBFIRST)
+  {
+    writeLSBFIRST(data & 0xFF);
+    data >>= 8;
+    writeLSBFIRST(data & 0xFF);
+    data >>= 8;
+    writeLSBFIRST(data & 0xFF);
+  }
+  else
+  {
+    writeMSBFIRST((data >> 16) & 0xFF);
+    writeMSBFIRST((data >> 8)  & 0xFF);
+    writeMSBFIRST(data & 0xFF);
+  }
+  return 3;
+}
+
+
+//  EXPERIMENTAL 0.3.3
+size_t FastShiftOut::write32(uint32_t data)
+{
+  if (_bitOrder == LSBFIRST)
+  {
+    writeLSBFIRST(data & 0xFF);
+    data >>= 8;
+    writeLSBFIRST(data & 0xFF);
+    data >>= 8;
+    writeLSBFIRST(data & 0xFF);
+    data >>= 8;
+    writeLSBFIRST(data & 0xFF);
+  }
+  else
+  {
+    writeMSBFIRST((data >> 24) & 0xFF);
+    writeMSBFIRST((data >> 16) & 0xFF);
+    writeMSBFIRST((data >> 8)  & 0xFF);
+    writeMSBFIRST(data & 0xFF);
+  }
+  return 4;
+}
+
+
+//  EXPERIMENTAL 0.3.3
+size_t FastShiftOut::write(uint8_t * array, size_t size)
 {
   size_t n = 0;
   if (_bitOrder == LSBFIRST)
   {
     for (size_t i = size; i > 0; )      //  from end to begin ????
     {
       i--;
-      n += writeLSBFIRST(buffer[i]);
+      writeLSBFIRST(array[i]);
     }
   }
   else
   {
     for (size_t i = 0; i < size; i++)   //  from begin to end..
     {
-      n += writeMSBFIRST(buffer[i]);
+      writeMSBFIRST(array[i]);
     }
   }
-  return n;
+  return size;
 }
-*/
+
+
+uint8_t FastShiftOut::lastWritten(void)
+{
+  return _lastValue;
+}
+
+
+bool FastShiftOut::setBitOrder(const uint8_t bitOrder)
+{
+  if ((bitOrder == LSBFIRST) || (bitOrder == MSBFIRST))
+  {
+    _bitOrder = bitOrder;
+    return true;
+  };
+  return false;
+}
+
+
+uint8_t FastShiftOut::getBitOrder(void)
+{
+  return _bitOrder;
+}
+
 
 
 size_t FastShiftOut::writeLSBFIRST(uint8_t data)
@@ -137,28 +222,5 @@ size_t FastShiftOut::writeMSBFIRST(uint8_t data)
 }
 
 
-uint8_t FastShiftOut::lastWritten(void)
-{
-  return _lastValue;
-}
-
-
-bool FastShiftOut::setBitOrder(const uint8_t bitOrder)
-{
-  if ((bitOrder == LSBFIRST) || (bitOrder == MSBFIRST))
-  {
-    _bitOrder = bitOrder;
-    return true;
-  };
-  return false;
-}
-
-
-uint8_t FastShiftOut::getBitOrder(void)
-{
-  return _bitOrder;
-}
-
-
 //  -- END OF FILE --
 
diff --git a/FastShiftOut.h b/FastShiftOut.h
@@ -2,7 +2,7 @@
 //
 //    FILE: FastShiftOut.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.3.2
+// VERSION: 0.3.3
 // PURPOSE: shiftOut class that implements the Print interface
 //    DATE: 2013-08-22
 //     URL: https://github.com/RobTillaart/FastShiftOut
@@ -11,7 +11,7 @@
 #include "Arduino.h"
 #include "Print.h"
 
-#define FASTSHIFTOUT_LIB_VERSION        (F("0.3.2"))
+#define FASTSHIFTOUT_LIB_VERSION        (F("0.3.3"))
 
 
 class FastShiftOut : public Print
@@ -21,14 +21,19 @@ class FastShiftOut : public Print
   FastShiftOut(uint8_t dataOut, uint8_t clockPin, uint8_t bitOrder = LSBFIRST);
 
   size_t  write(uint8_t data);
-  //  experimental
-  //  size_t write(const uint8_t \*buffer, size_t size);
   uint8_t lastWritten(void);
 
+  //  EXPERIMENTAL (wrappers)
+  size_t  write16(uint16_t data);
+  size_t  write24(uint32_t data);
+  size_t  write32(uint32_t data);
+  size_t  write(uint8_t * array, size_t size);
+
+  //  META
   bool    setBitOrder(uint8_t bitOrder);
   uint8_t getBitOrder(void);
 
-  // overrule bitOrder (most optimized).
+  //  overrule bitOrder, most optimized.
   size_t  writeLSBFIRST(uint8_t data);
   size_t  writeMSBFIRST(uint8_t data);
 

diff --git a/README.md b/README.md
@@ -13,42 +13,56 @@
 
 Arduino library for **AVR** optimized shiftOut - e.g. 74HC595.
 
-Related libraries
-- https://github.com/RobTillaart/FastShiftIn
-- https://github.com/RobTillaart/FastShiftInOut
-- https://github.com/RobTillaart/ShiftInSlow
-- https://github.com/RobTillaart/ShiftOutSlow
-
 
 ## Description
 
-FastShiftOut is a class that has optimized code for AVR to shift out data faster 
+FastShiftOut is a class that has optimized code (AVR only) to shift out data faster 
 than the normal **shiftOut()** function.
 It speeds up the shift using low level ports and masks. These are predetermined
 in the constructor of the FastShiftOut object.
 
 If not an **ARDUINO_ARCH_AVR** or **ARDUINO_ARCH_MEGAAVR** the class falls back 
 to the default shiftOut() implementation. 
 
+The library allows to set (and get) the bitOrder and apply this to multiple write()
+calls. It also provide access to **writeLSBFIRST()** and **writeMSBFIRST()** which 
+are the low level workers and most optimized code (so far).
+
+The library provides wrapper functions to write multi-byte variables. 
+These are write16(), write24(), write32() and write(array, size).
+The latter is used to shift out any size object.
+
 
-## Performance
+### Performance
 
-The performance of **write()** is substantially faster than the default Arduino 
-**shiftOut()**, but not as fast as HW SPI. 
-Exact how big the performance gain is can be seen with the example sketch.
+The performance of **write()** is substantially faster for **AVR** than the default 
+Arduino **shiftOut()**, but not as fast as HW SPI. 
+Exact how large the performance gain is can be seen with the example sketch.
 It does a comparison and shows how the class is to be used.
 
 Time in microseconds, Arduino UNO
 
-|  function                |  0.2.4  |   0.3.1  |
-|:-------------------------|--------:|---------:|
-|  write()                 |  21.66  |   22.48  |
-|  writeLSBFIRST()         |  22.94  |   23.37  |
-|  writeMSBFIRST()         |  20.30  |   21.86  |
-|  reference shiftOut()    |  89.74  |   89.74  |
-|  println("Hello world")  |         |  328.92  |
-|  println(1357)           |         |  313.56  |
-|  println(3.14159265, 4)  |         |  717.36  |
+|  function                |  0.2.4  |   0.3.1  |   0.3.3  |
+|:-------------------------|--------:|---------:|---------:|
+|  write()                 |  21.66  |   22.48  |   22.37  |
+|  writeLSBFIRST()         |  22.94  |   23.37  |   23.26  |
+|  writeMSBFIRST()         |  20.30  |   21.86  |   21.75  |
+|  reference shiftOut()    |  89.74  |   89.74  |   89.60  |
+|  println("Hello world")  |         |  328.92  |  328.92  |
+|  println(1357)           |         |  313.56  |  311.68  |
+|  println(3.14159265, 4)  |         |  717.36  |  716.04  |
+
+
+Note: 0.3.3 has improved the measurement, not the code sec.
+
+
+### Related
+
+- https://github.com/RobTillaart/FastShiftIn
+- https://github.com/RobTillaart/FastShiftInOut
+- https://github.com/RobTillaart/FastShiftOut
+- https://github.com/RobTillaart/ShiftInSlow
+- https://github.com/RobTillaart/ShiftOutSlow
 
 
 ## Interface
@@ -57,27 +71,53 @@ Time in microseconds, Arduino UNO
 #include "FastShiftOut.h"
 ```
 
-#### Functions
+### Constructor
 
 - **FastShiftOut(uint8_t dataOut, uint8_t clockPin, uint8_t bitOrder = LSBFIRST)** Constructor.
-- **size_t write(const uint8_t data)** send a byte, also the workhorse of the **Print** interface.
+
+### Functions
+
+- **size_t write(uint8_t data)** send a byte, also the workhorse of the **Print** interface.
+- **size_t write16(uint16_t data)** send 2 bytes.
+- **size_t write24(uint32_t data)** send 3 bytes.
+- **size_t write32(uint32_t data)** send 4 bytes.
+- **size_t write(uint8_t \*array, size_t size)** send size bytes.
 - **uint8_t lastWritten()** returns last byte written.
+
+### Meta
+
 - **bool setBitOrder(uint8_t bitOrder)** set LSBFIRST or MSBFIRST. Returns false for other values.
 - **uint8_t getBitOrder(void)** returns LSBFIRST or MSBFIRST.
-- **size_t writeLSBFIRST(const uint8_t data);**  most optimized.
-- **size_t writeMSBFIRST(const uint8_t data);**  most optimized.
+- **size_t writeLSBFIRST(uint8_t data)**  most optimized.
+- **size_t writeMSBFIRST(uint8_t data)**  most optimized.
 
 
 As a FastShiftOut object implements the Print interface, one can also call
 
-- **FSO.print(any type);** or 
-- **FSO.println(any type);** 
+- **FSO.print(any type)** or 
+- **FSO.println(any type)** 
 
 to send e.g. a float with 4 digits over the line, or some text string. 
 
 Note: **FSO.print()** returns the number of characters printed, including an optional \\r or \\n.
 
 
+### Byte order
+
+The functions **write16()**, **write24()** and **write32()** of this library assume
+that the BIT-order is also the BYTE-order.
+This is not always the case as an n-byte element can have n! == factorial(n)
+distinct byte orders.
+
+So **write16()** can have two, **write24()** can have six and **write32()** can even have 
+(in theory) 24 distinct byte orders. Although LSB and MSB are the most common,
+other byte orders exist, and sometimes one explicitly wants to reorder the bytes.
+
+If the BIT-order is not the BYTE-order, the user has two options
+- call **write()** multiple times and merge the bytes in the order needed.
+- call **write32()** (a.o) and reorder the bytes in a separate function.
+
+
 ## Notes
 
 - The optimizations are AVR only for now, other platforms may follow.
@@ -90,15 +130,19 @@ pull up resistors, especially if wires are exceeding 10 cm (4").
 
 #### Must
 
+- keep in sync with FastShiftIn()
+
 #### Should
 
 - extend unit tests
 
 #### Could
 
+- investigate separate **BYTE**-order, 
+  - only MSBFirst and LSBFirst
+  - **void setByteOrder()** + **uint8_t getByteOrder()**
+- investigate ESP32 optimization readLSBFIRST readMSBFIRST
 - performance ESP32
-- check optimized ESP32
-- add **size_t write(const uint8_t \*buffer, size_t size)**
 - example schema
 
 #### Wont