Initial Release

.gitignore

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+.idea
+.vscode
+cmake-*

.gitmodules

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+[submodule "lwip"]
+	path = lib/lwip
+	url = https://git.savannah.nongnu.org/git/lwip.git
+[submodule "lib/lwip"]
+	url = git://git.savannah.nongnu.org/lwip.git

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.12)
+
+# Pull in PICO SDK (must be before project)
+include(pico_sdk_import.cmake)
+
+project(pico_extras C CXX)
+
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
+
+# Initialize the SDK
+pico_sdk_init()
+
+pico_is_top_level_project(PICO_EXTRAS_TOP_LEVEL_PROJECT)
+
+add_library(pico_extras_included INTERFACE)
+target_compile_definitions(pico_extras_included INTERFACE
+        -DPICO_EXTRAS=1
+)
+
+pico_add_platform_library(pico_extras_included)
+
+if (NOT PICO_EXTRAS_PATH)
+    set(PICO_EXTRAS_PATH ${CMAKE_CURRENT_LIST_DIR})
+endif()
+set(PICO_EXTRAS_PATH "${PICO_EXTRAS_PATH}" CACHE PATH "Path to Pico Extras")
+
+add_subdirectory(src)
+
+if (PICO_EXTRAS_TESTS_ENABLED OR PICO_EXTRAS_TOP_LEVEL_PROJECT)
+    add_subdirectory(test)
+endif ()

LICENSE.TXT

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+Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+   disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
+   disclaimer in the documentation and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products
+   derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+This repo has additional libraries that are not yet ready for inclusion the Pico SDK proper,
+or are just useful but don't necessarily belong in the Pico SDK.
+
+Note that any API here is a work in progress and subject to change.
+
+See [pico-playground](https://github.com/raspberrypi/pico-playground) for buildable example code using these extra libraries.
+
+
+Library|Description 
+---|---
+[hardware_rosc](src/rp2_common/hardware_rosc)| API for the ring oscillator
+[lwip](src/rp2_common/lwip)| [LWIP Lightweight IP Library](https://savannah.nongnu.org/projects/lwip/) packed as an INTERFACE library for use with the Pico SDK
+[pico_audio](src/common/pico_audio)|Audio output support; this is highly functional, but the API is subject to change 
+   [pico_audio_i2s](src/rp2_common/pico_audio_spdif)|Audio output via I2S on 3 GPIOs using PIO. Arbitrary frequency
+   [pico_audio_pwm](src/rp2_common/pico_audio_spdif)|Audio output via (PIO) PWM. Currently a bit limited in frequency support (it was developed on FPGA to do 22050Hz at 48Mhz system clock). It does however support error diffusion dithering and noise shaping with 16x oversampling to give surprsingly good audio quality. This code will be split to provide both a fixed frequencie(s) version and a slightly slower but rather better arbitrary frequency version supporting ever higher carrier frequencies 
+   [pico_audio_spdif](src/rp2_common/pico_audio_spdif)|Audio output in S/PDIF on a GPIO using PIO. Supports up to 192khz stereo. Consumed OK in test, haven't tried it with real hardware
+[pico_sd_card](src/rp2_common/pico_sd_card)|1 and 4 bit SDIO support using PIO. This is functional (currently writing is only 1 bit), but the the code is very much prototype and the API is just a placeholder - the command set needs to be separated from the SDIO and shared with SPI
+[pico_sleep](src/rp2_common/pico_sleep)|Low power related APIs, WIP because they are not sufficiently generic and also only handle core 0
+[pico_scanvideo](src/common/pico_scanvideo)|Support for video output where every pixel is _scanned out_ everry frame. VGA/DPI support is highgly functional and stable, but the API is subject to change
+   [pico_scanvideo_dbi](src/rp2_common/pico_scanvideo_dbi)| currently non-compiling... placeholder for adding scanvideo over MIPI DBI support.
+   [pico_scanvideo_dpi](src/rp2_common/pico_scanvideo_dbi)| Highly functional and stable support for parallel RGB output and VSYNC/HSYNC/DEN/CLOCK for VGA/DPI.
+[pico_util_buffer](src/common/pico_util_buffer)|Rather incomplete buffer abstraction, used by pico_audio and pico_scanvideo
+[platypus](src/common/platypus)| Decoder for a custom image compression format suitable for dithered images (good for RGB555) and suitable for decoding on RP2040 at scanline speeds ... i.e you can easily decode a 320x240 image 60x per second to avoid storing the uncompressed image for scanout video. It gets about 50% compression (but is designed only for 4x4 fixed dithered RGB555 images, so is somewhat specific!). TODO add the encoder here :-)
+[usb_device](src/rp2_common/usb_device), [usb_common](src/rp2_common/usb_common)| The custom and somewhat minimal USB device stack used in the bootrom. We now use TinyUSB in the Pico SDK but kep here for posterit
+[usb_device_msc](src/rp2_common/usb_device_msc)| USB Mass Storage Class implementation using _usb_device_
+
+
+You can add Pico Extras to your project similarly to the SDK (copying [external/pico_extras_import.cmake](external/pico_extras_import.cmake) into your project)
+having set the `PICO_EXTRAS_PATH` variable in your environment or via cmake variable.
+
+```cmake
+cmake_minimum_required(VERSION 3.12)
+
+# Pull in PICO SDK (must be before project)
+include(pico_sdk_import.cmake)
+
+# We also need PICO EXTRAS
+include(pico_extras_import.cmake)
+
+project(pico_playground C CXX)
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
+``` 
+
+Alternative you can inject it into an existing project without modifying it via `PICO_CMAKE_POST_LIST_DIRS`
+ by passing `-DPICO_SDK_POST_LIST_DIRS=/path/to/pico_extras` to cmake

external/pico_extras_import.cmake

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+# This is a copy of <PICO_EXTRAS_PATH>/external/pico_extras_import.cmake
+
+# This can be dropped into an external project to help locate pico-extras
+# It should be include()ed prior to project()
+
+if (DEFINED ENV{PICO_EXTRAS_PATH} AND (NOT PICO_EXTRAS_PATH))
+    set(PICO_EXTRAS_PATH $ENV{PICO_EXTRAS_PATH})
+    message("Using PICO_EXTRAS_PATH from environment ('${PICO_EXTRAS_PATH}')")
+endif ()
+
+if (DEFINED ENV{PICO_EXTRAS_FETCH_FROM_GIT} AND (NOT PICO_EXTRAS_FETCH_FROM_GIT))
+    set(PICO_EXTRAS_FETCH_FROM_GIT $ENV{PICO_EXTRAS_FETCH_FROM_GIT})
+    message("Using PICO_EXTRAS_FETCH_FROM_GIT from environment ('${PICO_EXTRAS_FETCH_FROM_GIT}')")
+endif ()
+
+if (DEFINED ENV{PICO_EXTRAS_FETCH_FROM_GIT_PATH} AND (NOT PICO_EXTRAS_FETCH_FROM_GIT_PATH))
+    set(PICO_EXTRAS_FETCH_FROM_GIT_PATH $ENV{PICO_EXTRAS_FETCH_FROM_GIT_PATH})
+    message("Using PICO_EXTRAS_FETCH_FROM_GIT_PATH from environment ('${PICO_EXTRAS_FETCH_FROM_GIT_PATH}')")
+endif ()
+
+if (NOT PICO_EXTRAS_PATH)
+    if (PICO_EXTRAS_FETCH_FROM_GIT)
+        include(FetchContent)
+        set(FETCHCONTENT_BASE_DIR_SAVE ${FETCHCONTENT_BASE_DIR})
+        if (PICO_EXTRAS_FETCH_FROM_GIT_PATH)
+            get_filename_component(FETCHCONTENT_BASE_DIR "${PICO_EXTRAS_FETCH_FROM_GIT_PATH}" REALPATH BASE_DIR "${CMAKE_SOURCE_DIR}")
+        endif ()
+        FetchContent_Declare(
+                PICO_EXTRAS
+                GIT_REPOSITORY https://github.com/raspberrypi/pico-extras
+                GIT_TAG master
+        )
+        if (NOT PICO_EXTRAS)
+            message("Downloading PICO EXTRAS")
+            FetchContent_Populate(PICO_EXTRAS)
+            set(PICO_EXTRAS_PATH ${PICO_EXTRAS_SOURCE_DIR})
+        endif ()
+        set(FETCHCONTENT_BASE_DIR ${FETCHCONTENT_BASE_DIR_SAVE})
+    else ()
+        if (PICO_SDK_PATH AND EXISTS "${PICO_SDK_PATH}/../pico-extras")
+            set(PICO_EXTRAS_PATH ${PICO_SDK_PATH}/../pico-extras)
+            message("Defaulting PICO_EXTRAS_PATH as sibling of PICO_SDK_PATH: ${PICO_EXTRAS_PATH}")
+        else()
+            message(FATAL_ERROR
+                    "PICO EXTRAS location was not specified. Please set PICO_EXTRAS_PATH or set PICO_EXTRAS_FETCH_FROM_GIT to on to fetch from git."
+                    )
+        endif()
+    endif ()
+endif ()
+
+set(PICO_EXTRAS_PATH "${PICO_EXTRAS_PATH}" CACHE PATH "Path to the PICO EXTRAS")
+set(PICO_EXTRAS_FETCH_FROM_GIT "${PICO_EXTRAS_FETCH_FROM_GIT}" CACHE BOOL "Set to ON to fetch copy of PICO EXTRAS from git if not otherwise locatable")
+set(PICO_EXTRAS_FETCH_FROM_GIT_PATH "${PICO_EXTRAS_FETCH_FROM_GIT_PATH}" CACHE FILEPATH "location to download EXTRAS")
+
+get_filename_component(PICO_EXTRAS_PATH "${PICO_EXTRAS_PATH}" REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
+if (NOT EXISTS ${PICO_EXTRAS_PATH})
+    message(FATAL_ERROR "Directory '${PICO_EXTRAS_PATH}' not found")
+endif ()
+
+set(PICO_EXTRAS_PATH ${PICO_EXTRAS_PATH} CACHE PATH "Path to the PICO EXTRAS" FORCE)
+
+add_subdirectory(${PICO_EXTRAS_PATH} pico_extras)

pico_sdk_import.cmake

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+# This is a copy of <PICO_SDK_PATH>/external/pico_sdk_import.cmake
+
+# This can be dropped into an external project to help locate this SDK
+# It should be include()ed prior to project()
+
+if (DEFINED ENV{PICO_SDK_PATH} AND (NOT PICO_SDK_PATH))
+    set(PICO_SDK_PATH $ENV{PICO_SDK_PATH})
+    message("Using PICO_SDK_PATH from environment ('${PICO_SDK_PATH}')")
+endif ()
+
+if (DEFINED ENV{PICO_SDK_FETCH_FROM_GIT} AND (NOT PICO_SDK_FETCH_FROM_GIT))
+    set(PICO_SDK_FETCH_FROM_GIT $ENV{PICO_SDK_FETCH_FROM_GIT})
+    message("Using PICO_SDK_FETCH_FROM_GIT from environment ('${PICO_SDK_FETCH_FROM_GIT}')")
+endif ()
+
+if (DEFINED ENV{PICO_SDK_FETCH_FROM_GIT_PATH} AND (NOT PICO_SDK_FETCH_FROM_GIT_PATH))
+    set(PICO_SDK_FETCH_FROM_GIT_PATH $ENV{PICO_SDK_FETCH_FROM_GIT_PATH})
+    message("Using PICO_SDK_FETCH_FROM_GIT_PATH from environment ('${PICO_SDK_FETCH_FROM_GIT_PATH}')")
+endif ()
+
+set(PICO_SDK_PATH "${PICO_SDK_PATH}" CACHE PATH "Path to the PICO SDK")
+set(PICO_SDK_FETCH_FROM_GIT "${PICO_SDK_FETCH_FROM_GIT}" CACHE BOOL "Set to ON to fetch copy of PICO SDK from git if not otherwise locatable")
+set(PICO_SDK_FETCH_FROM_GIT_PATH "${PICO_SDK_FETCH_FROM_GIT_PATH}" CACHE FILEPATH "location to download SDK")
+
+if (NOT PICO_SDK_PATH)
+    if (PICO_SDK_FETCH_FROM_GIT)
+        include(FetchContent)
+        set(FETCHCONTENT_BASE_DIR_SAVE ${FETCHCONTENT_BASE_DIR})
+        if (PICO_SDK_FETCH_FROM_GIT_PATH)
+            get_filename_component(FETCHCONTENT_BASE_DIR "${PICO_SDK_FETCH_FROM_GIT_PATH}" REALPATH BASE_DIR "${CMAKE_SOURCE_DIR}")
+        endif ()
+        FetchContent_Declare(
+                pico_sdk
+                GIT_REPOSITORY https://github.com/raspberrypi/pico-sdk
+                GIT_TAG master
+        )
+        if (NOT pico_sdk)
+            message("Downloading PICO SDK")
+            FetchContent_Populate(pico_sdk)
+            set(PICO_SDK_PATH ${pico_sdk_SOURCE_DIR})
+        endif ()
+        set(FETCHCONTENT_BASE_DIR ${FETCHCONTENT_BASE_DIR_SAVE})
+    else ()
+        message(FATAL_ERROR
+                "PICO SDK location was not specified. Please set PICO_SDK_PATH or set PICO_SDK_FETCH_FROM_GIT to on to fetch from git."
+                )
+    endif ()
+endif ()
+
+get_filename_component(PICO_SDK_PATH "${PICO_SDK_PATH}" REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
+if (NOT EXISTS ${PICO_SDK_PATH})
+    message(FATAL_ERROR "Directory '${PICO_SDK_PATH}' not found")
+endif ()
+
+set(PICO_SDK_INIT_CMAKE_FILE ${PICO_SDK_PATH}/pico_sdk_init.cmake)
+if (NOT EXISTS ${PICO_SDK_INIT_CMAKE_FILE})
+    message(FATAL_ERROR "Directory '${PICO_SDK_PATH}' does not appear to contain the PICO SDK")
+endif ()
+
+set(PICO_SDK_PATH ${PICO_SDK_PATH} CACHE PATH "Path to the PICO SDK" FORCE)
+
+include(${PICO_SDK_INIT_CMAKE_FILE})

src/CMakeLists.txt

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+add_subdirectory(common)
+if (PICO_ON_DEVICE)
+    add_subdirectory(rp2_common)
+endif()

src/common/CMakeLists.txt

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+add_subdirectory(pico_audio)
+add_subdirectory(pico_scanvideo)
+add_subdirectory(pico_sd_card)
+add_subdirectory(pico_util_buffer)
+add_subdirectory(platypus)

src/common/pico_audio/CMakeLists.txt

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+if (NOT TARGET pico_audio_headers)
+    add_library(pico_audio_headers INTERFACE)
+    target_include_directories(pico_audio_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
+    target_link_libraries(pico_audio_headers INTERFACE pico_util_buffer)
+endif()
+
+if (NOT TARGET pico_audio)
+    add_library(pico_audio INTERFACE)
+
+    target_sources(pico_audio INTERFACE
+            ${CMAKE_CURRENT_LIST_DIR}/audio.cpp
+            $<$<NOT:$<BOOL:${PICO_NO_HARDWARE}>>:${CMAKE_CURRENT_LIST_DIR}/audio_utils.S>
+    )
+
+    target_link_libraries(pico_audio INTERFACE pico_audio_headers pico_sync)
+endif()