From 2cc1a6a1dabfd3359af80321dc53cf953383685f Mon Sep 17 00:00:00 2001
From: me-no-dev <hristo@espressif.com>
Date: Sun, 13 Nov 2016 16:53:56 +0200
Subject: [PATCH] add shiftIn shiftOut

thanks @ladyada
---
 cores/esp32/Arduino.h      |  3 +++
 cores/esp32/wiring_shift.c | 50 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 cores/esp32/wiring_shift.c

diff --git a/cores/esp32/Arduino.h b/cores/esp32/Arduino.h
index 485238c5..7906b161 100644
--- a/cores/esp32/Arduino.h
+++ b/cores/esp32/Arduino.h
@@ -119,6 +119,9 @@ typedef bool boolean;
 typedef uint8_t byte;
 typedef unsigned int word;
 
+uint8_t shiftIn(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder);
+void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val);
+
 #ifdef __cplusplus
 }
 
diff --git a/cores/esp32/wiring_shift.c b/cores/esp32/wiring_shift.c
new file mode 100644
index 00000000..44c13700
--- /dev/null
+++ b/cores/esp32/wiring_shift.c
@@ -0,0 +1,50 @@
+/*
+ wiring_shift.c - shiftOut() function
+ Part of Arduino - http://www.arduino.cc/
+ Copyright (c) 2005-2006 David A. Mellis
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ Lesser General Public License for more details.
+ You should have received a copy of the GNU Lesser General
+ Public License along with this library; if not, write to the
+ Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ Boston, MA  02111-1307  USA
+ $Id: wiring.c 248 2007-02-03 15:36:30Z mellis $
+ */
+ 
+#include "esp32-hal.h"
+#include "wiring_private.h"
+
+uint8_t shiftIn(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder) {
+    uint8_t value = 0;
+    uint8_t i;
+
+    for(i = 0; i < 8; ++i) {
+        digitalWrite(clockPin, HIGH);
+        if(bitOrder == LSBFIRST)
+            value |= digitalRead(dataPin) << i;
+        else
+            value |= digitalRead(dataPin) << (7 - i);
+        digitalWrite(clockPin, LOW);
+    }
+    return value;
+}
+
+void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val) {
+    uint8_t i;
+
+    for(i = 0; i < 8; i++) {
+        if(bitOrder == LSBFIRST)
+            digitalWrite(dataPin, !!(val & (1 << i)));
+        else
+            digitalWrite(dataPin, !!(val & (1 << (7 - i))));
+
+        digitalWrite(clockPin, HIGH);
+        digitalWrite(clockPin, LOW);
+    }
+}