Add I2S class support (#7874)

Fixes #427

Adds a basic I2S class based off of the Arduino-SAMD core.  The raw
i2s_xxx functions are still a better  way to use I2S due to their
flexibility, but this will allow basic Arduino sketches to work.

cores/esp8266/core_esp8266_i2s.cpp

@@ -24,7 +24,7 @@
 #include "osapi.h"
 #include "ets_sys.h"
 #include "i2s_reg.h"
-#include "i2s.h"
+#include "core_esp8266_i2s.h"
 
 extern "C" {
 
@@ -194,11 +194,11 @@ static void ICACHE_RAM_ATTR i2s_slc_isr(void) {
 }
 
 void i2s_set_callback(void (*callback) (void)) {
-  tx->callback = callback;
+  if (tx) tx->callback = callback;
 }
 
 void i2s_rx_set_callback(void (*callback) (void)) {
-  rx->callback = callback;
+  if (rx) rx->callback = callback;
 }
 
 static bool _alloc_channel(i2s_state_t *ch) {
@@ -343,7 +343,7 @@ bool i2s_write_lr(int16_t left, int16_t right){
 
 // writes a buffer of frames into the DMA memory, returns the amount of frames written
 // A frame is just a int16_t for mono, for stereo a frame is two int16_t, one for each channel.
-static uint16_t _i2s_write_buffer(int16_t *frames, uint16_t frame_count, bool mono, bool nb) {
+static uint16_t _i2s_write_buffer(const int16_t *frames, uint16_t frame_count, bool mono, bool nb) {
     uint16_t frames_written=0;
 
     while(frame_count>0) {
@@ -401,13 +401,13 @@ static uint16_t _i2s_write_buffer(int16_t *frames, uint16_t frame_count, bool mo
     return frames_written;
 }
 
-uint16_t i2s_write_buffer_mono_nb(int16_t *frames, uint16_t frame_count) { return _i2s_write_buffer(frames, frame_count, true, true); }
+uint16_t i2s_write_buffer_mono_nb(const int16_t *frames, uint16_t frame_count) { return _i2s_write_buffer(frames, frame_count, true, true); }
 
-uint16_t i2s_write_buffer_mono(int16_t *frames, uint16_t frame_count) { return _i2s_write_buffer(frames, frame_count, true, false); }
+uint16_t i2s_write_buffer_mono(const int16_t *frames, uint16_t frame_count) { return _i2s_write_buffer(frames, frame_count, true, false); }
 
-uint16_t i2s_write_buffer_nb(int16_t *frames, uint16_t frame_count) { return _i2s_write_buffer(frames, frame_count, false, true); }
+uint16_t i2s_write_buffer_nb(const int16_t *frames, uint16_t frame_count) { return _i2s_write_buffer(frames, frame_count, false, true); }
 
-uint16_t i2s_write_buffer(int16_t *frames, uint16_t frame_count) { return _i2s_write_buffer(frames, frame_count, false, false); }
+uint16_t i2s_write_buffer(const int16_t *frames, uint16_t frame_count) { return _i2s_write_buffer(frames, frame_count, false, false); }
 
 bool i2s_read_sample(int16_t *left, int16_t *right, bool blocking) {
   if (!rx) {

cores/esp8266/core_esp8266_i2s.h

@@ -0,0 +1,81 @@
+/* 
+  i2s.h - Software I2S library for esp8266
+
+  Copyright (c) 2015 Hristo Gochkov. All rights reserved.
+  This file is part of the esp8266 core for Arduino environment.
+ 
+  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+#ifndef I2S_h
+#define I2S_h
+
+#define I2S_HAS_BEGIN_RXTX_DRIVE_CLOCKS 1
+
+/*
+How does this work? Basically, to get sound, you need to:
+- Connect an I2S codec to the I2S pins on the ESP.
+- Start up a thread that's going to do the sound output
+- Call i2s_set_bits() if you want to enable 24-bit mode
+- Call i2s_begin()
+- Call i2s_set_rate() with the sample rate you want.
+- Generate sound and call i2s_write_sample() with 32-bit samples.
+The 32bit samples basically are 2 16-bit signed values (the analog values for
+the left and right channel) concatenated as (Rout<<16)+Lout
+
+i2s_write_sample will block when you're sending data too quickly, so you can just
+generate and push data as fast as you can and i2s_write_sample will regulate the
+speed.
+*/
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+bool i2s_set_bits(int bits); // Set bits per sample, only 16 or 24 supported.  Call before begin.
+// Note that in 24 bit mode each sample must be left-aligned (i.e. 0x00000000 .. 0xffffff00) as the
+// hardware shifts starting at bit 31, not bit 23.
+
+void i2s_begin(); // Enable TX only, for compatibility
+bool i2s_rxtx_begin(bool enableRx, bool enableTx); // Allow TX and/or RX, returns false on OOM error
+bool i2s_rxtxdrive_begin(bool enableRx, bool enableTx, bool driveRxClocks, bool driveTxClocks);
+void i2s_end();
+void i2s_set_rate(uint32_t rate);//Sample Rate in Hz (ex 44100, 48000)
+void i2s_set_dividers(uint8_t div1, uint8_t div2);//Direct control over output rate
+float i2s_get_real_rate();//The actual Sample Rate on output
+bool i2s_write_sample(uint32_t sample);//32bit sample with channels being upper and lower 16 bits (blocking when DMA is full)
+bool i2s_write_sample_nb(uint32_t sample);//same as above but does not block when DMA is full and returns false instead
+bool i2s_write_lr(int16_t left, int16_t right);//combines both channels and calls i2s_write_sample with the result
+bool i2s_read_sample(int16_t *left, int16_t *right, bool blocking); // RX data returned in both 16-bit outputs.
+bool i2s_is_full();//returns true if DMA is full and can not take more bytes (overflow)
+bool i2s_is_empty();//returns true if DMA is empty (underflow)
+bool i2s_rx_is_full();
+bool i2s_rx_is_empty();
+uint16_t i2s_available();// returns the number of samples than can be written before blocking
+uint16_t i2s_rx_available();// returns the number of samples than can be written before blocking
+void i2s_set_callback(void (*callback) (void));
+void i2s_rx_set_callback(void (*callback) (void));
+
+// writes a buffer of frames into the DMA memory, returns the amount of frames written
+// A frame is just a int16_t for mono, for stereo a frame is two int16_t, one for each channel.
+uint16_t i2s_write_buffer_mono(const int16_t *frames, uint16_t frame_count);
+uint16_t i2s_write_buffer_mono_nb(const int16_t *frames, uint16_t frame_count);
+uint16_t i2s_write_buffer(const int16_t *frames, uint16_t frame_count);
+uint16_t i2s_write_buffer_nb(const int16_t *frames, uint16_t frame_count);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

cores/esp8266/i2s.h

@@ -1,81 +1,12 @@
-/* 
-  i2s.h - Software I2S library for esp8266
+// This include file is a hack to ensure backward compatibility with
+// pre 3.0.0 versions of the core.  There was a *lowercase* "i2s.h"
+// header which was in this directory, now renamed to "core_esp82i66s.h"
+// But, the I2S class has a header, "I2S.h" in uppercase.  On Linux
+// the two names are different, but on Windows it's case-insensitive
+// so the names conflict.
+//
+// Avoid the issue by preserving the old i2s.h file and have it redirect
+// to I2S.h which will give the ESP8266-specific functions as well as
+// the generic I2S class.
 
-  Copyright (c) 2015 Hristo Gochkov. All rights reserved.
-  This file is part of the esp8266 core for Arduino environment.
- 
-  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-*/
-#ifndef I2S_h
-#define I2S_h
-
-#define I2S_HAS_BEGIN_RXTX_DRIVE_CLOCKS 1
-
-/*
-How does this work? Basically, to get sound, you need to:
-- Connect an I2S codec to the I2S pins on the ESP.
-- Start up a thread that's going to do the sound output
-- Call i2s_set_bits() if you want to enable 24-bit mode
-- Call i2s_begin()
-- Call i2s_set_rate() with the sample rate you want.
-- Generate sound and call i2s_write_sample() with 32-bit samples.
-The 32bit samples basically are 2 16-bit signed values (the analog values for
-the left and right channel) concatenated as (Rout<<16)+Lout
-
-i2s_write_sample will block when you're sending data too quickly, so you can just
-generate and push data as fast as you can and i2s_write_sample will regulate the
-speed.
-*/
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-bool i2s_set_bits(int bits); // Set bits per sample, only 16 or 24 supported.  Call before begin.
-// Note that in 24 bit mode each sample must be left-aligned (i.e. 0x00000000 .. 0xffffff00) as the
-// hardware shifts starting at bit 31, not bit 23.
-
-void i2s_begin(); // Enable TX only, for compatibility
-bool i2s_rxtx_begin(bool enableRx, bool enableTx); // Allow TX and/or RX, returns false on OOM error
-bool i2s_rxtxdrive_begin(bool enableRx, bool enableTx, bool driveRxClocks, bool driveTxClocks);
-void i2s_end();
-void i2s_set_rate(uint32_t rate);//Sample Rate in Hz (ex 44100, 48000)
-void i2s_set_dividers(uint8_t div1, uint8_t div2);//Direct control over output rate
-float i2s_get_real_rate();//The actual Sample Rate on output
-bool i2s_write_sample(uint32_t sample);//32bit sample with channels being upper and lower 16 bits (blocking when DMA is full)
-bool i2s_write_sample_nb(uint32_t sample);//same as above but does not block when DMA is full and returns false instead
-bool i2s_write_lr(int16_t left, int16_t right);//combines both channels and calls i2s_write_sample with the result
-bool i2s_read_sample(int16_t *left, int16_t *right, bool blocking); // RX data returned in both 16-bit outputs.
-bool i2s_is_full();//returns true if DMA is full and can not take more bytes (overflow)
-bool i2s_is_empty();//returns true if DMA is empty (underflow)
-bool i2s_rx_is_full();
-bool i2s_rx_is_empty();
-uint16_t i2s_available();// returns the number of samples than can be written before blocking
-uint16_t i2s_rx_available();// returns the number of samples than can be written before blocking
-void i2s_set_callback(void (*callback) (void));
-void i2s_rx_set_callback(void (*callback) (void));
-
-// writes a buffer of frames into the DMA memory, returns the amount of frames written
-// A frame is just a int16_t for mono, for stereo a frame is two int16_t, one for each channel.
-uint16_t i2s_write_buffer_mono(int16_t *frames, uint16_t frame_count);
-uint16_t i2s_write_buffer_mono_nb(int16_t *frames, uint16_t frame_count);
-uint16_t i2s_write_buffer(int16_t *frames, uint16_t frame_count);
-uint16_t i2s_write_buffer_nb(int16_t *frames, uint16_t frame_count); 
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif
+#include "../../libraries/I2S/src/I2S.h"