[FEATURE] Basic implementation of Arduino's I2S library (#5304)

Basic version of Arduino's I2S library. We currently support only 16bps + 16000 Hz sampling frequency. Other bitrates and sample rates will print warning and continue to operate, however the resulting audio quality may be poor.
There will be further effort to fix these issues.

Author: PilnyTomas

.github/workflows/upload-idf-component.yml

@@ -0,0 +1,19 @@
+name: Push components to https://components.espressif.com
+on:
+  push:
+    tags:
+      - v*
+jobs:
+  upload_components:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          submodules: "recursive"
+
+      - name: Upload components to the component registry
+        uses: espressif/github-actions/upload_components@master
+        with:
+          name: arduino-esp32
+          namespace: espressif
+          api_token: ${{ secrets.IDF_COMPONENT_API_TOKEN }}

CMakeLists.txt

@@ -86,6 +86,7 @@ set(LIBRARY_SRCS
   libraries/HTTPClient/src/HTTPClient.cpp
   libraries/HTTPUpdate/src/HTTPUpdate.cpp
   libraries/LittleFS/src/LittleFS.cpp
+  libraries/I2S/src/I2S.cpp
   libraries/NetBIOS/src/NetBIOS.cpp
   libraries/Preferences/src/Preferences.cpp
   libraries/RainMaker/src/RMaker.cpp
@@ -162,7 +163,6 @@ set(BLE_SRCS
   libraries/BLE/src/GeneralUtils.cpp
   )
 
-
 set(includedirs
   variants/${IDF_TARGET}/
   cores/esp32/
@@ -179,6 +179,7 @@ set(includedirs
   libraries/HTTPClient/src
   libraries/HTTPUpdate/src
   libraries/LittleFS/src
+  libraries/I2S/src
   libraries/NetBIOS/src
   libraries/Preferences/src
   libraries/RainMaker/src
@@ -234,6 +235,8 @@ function(maybe_add_component component_name)
     endif()
 endfunction()
 
+maybe_add_component(esp-dsp)
+
 if(IDF_TARGET MATCHES "esp32" AND CONFIG_ESP_RMAKER_TASK_STACK)
     maybe_add_component(esp_rainmaker)
     maybe_add_component(qrcode)

boards.txt

@@ -5943,6 +5943,284 @@ adafruit_qtpy_esp32s2.menu.DebugLevel.debug.build.code_debug=4
 adafruit_qtpy_esp32s2.menu.DebugLevel.verbose=Verbose
 adafruit_qtpy_esp32s2.menu.DebugLevel.verbose.build.code_debug=5
 
+##############################################################
+
+adafruit_qtpy_esp32c3.name=Adafruit QT Py ESP32-C3
+adafruit_qtpy_esp32c3.vid.0=0x303a
+adafruit_qtpy_esp32c3.pid.0=0x1001
+
+adafruit_qtpy_esp32c3.upload.tool=esptool_py
+adafruit_qtpy_esp32c3.upload.maximum_size=1310720
+adafruit_qtpy_esp32c3.upload.maximum_data_size=327680
+adafruit_qtpy_esp32c3.upload.flags=
+adafruit_qtpy_esp32c3.upload.extra_flags=
+adafruit_qtpy_esp32c3.upload.use_1200bps_touch=false
+adafruit_qtpy_esp32c3.upload.wait_for_upload_port=false
+
+adafruit_qtpy_esp32c3.serial.disableDTR=false
+adafruit_qtpy_esp32c3.serial.disableRTS=false
+
+adafruit_qtpy_esp32c3.build.tarch=riscv32
+adafruit_qtpy_esp32c3.build.target=esp
+adafruit_qtpy_esp32c3.build.mcu=esp32c3
+adafruit_qtpy_esp32c3.build.core=esp32
+adafruit_qtpy_esp32c3.build.variant=adafruit_qtpy_esp32c3
+adafruit_qtpy_esp32c3.build.board=ADAFRUIT_QTPY_ESP32C3
+adafruit_qtpy_esp32c3.build.bootloader_addr=0x0
+
+adafruit_qtpy_esp32c3.build.cdc_on_boot=0
+adafruit_qtpy_esp32c3.build.f_cpu=160000000L
+adafruit_qtpy_esp32c3.build.flash_size=4MB
+adafruit_qtpy_esp32c3.build.flash_freq=80m
+adafruit_qtpy_esp32c3.build.flash_mode=dout
+adafruit_qtpy_esp32c3.build.boot=dout
+adafruit_qtpy_esp32c3.build.partitions=default
+adafruit_qtpy_esp32c3.build.defines=
+
+adafruit_qtpy_esp32c3.menu.CDCOnBoot.cdc=Enabled
+adafruit_qtpy_esp32c3.menu.CDCOnBoot.cdc.build.cdc_on_boot=1
+adafruit_qtpy_esp32c3.menu.CDCOnBoot.default=Disabled
+adafruit_qtpy_esp32c3.menu.CDCOnBoot.default.build.cdc_on_boot=0
+
+adafruit_qtpy_esp32c3.menu.PartitionScheme.default=Default 4MB with spiffs (1.2MB APP/1.5MB SPIFFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.default.build.partitions=default
+adafruit_qtpy_esp32c3.menu.PartitionScheme.defaultffat=Default 4MB with ffat (1.2MB APP/1.5MB FATFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.defaultffat.build.partitions=default_ffat
+adafruit_qtpy_esp32c3.menu.PartitionScheme.minimal=Minimal (1.3MB APP/700KB SPIFFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.minimal.build.partitions=minimal
+adafruit_qtpy_esp32c3.menu.PartitionScheme.no_ota=No OTA (2MB APP/2MB SPIFFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.no_ota.build.partitions=no_ota
+adafruit_qtpy_esp32c3.menu.PartitionScheme.no_ota.upload.maximum_size=2097152
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_3g=No OTA (1MB APP/3MB SPIFFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_3g.build.partitions=noota_3g
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_3g.upload.maximum_size=1048576
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_ffat=No OTA (2MB APP/2MB FATFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_ffat.build.partitions=noota_ffat
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_ffat.upload.maximum_size=2097152
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_3gffat=No OTA (1MB APP/3MB FATFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_3gffat.build.partitions=noota_3gffat
+adafruit_qtpy_esp32c3.menu.PartitionScheme.noota_3gffat.upload.maximum_size=1048576
+adafruit_qtpy_esp32c3.menu.PartitionScheme.huge_app=Huge APP (3MB No OTA/1MB SPIFFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.huge_app.build.partitions=huge_app
+adafruit_qtpy_esp32c3.menu.PartitionScheme.huge_app.upload.maximum_size=3145728
+adafruit_qtpy_esp32c3.menu.PartitionScheme.min_spiffs=Minimal SPIFFS (1.9MB APP with OTA/190KB SPIFFS)
+adafruit_qtpy_esp32c3.menu.PartitionScheme.min_spiffs.build.partitions=min_spiffs
+adafruit_qtpy_esp32c3.menu.PartitionScheme.min_spiffs.upload.maximum_size=1966080
+
+adafruit_qtpy_esp32c3.menu.CPUFreq.160=160MHz (WiFi)
+adafruit_qtpy_esp32c3.menu.CPUFreq.160.build.f_cpu=160000000L
+adafruit_qtpy_esp32c3.menu.CPUFreq.80=80MHz (WiFi)
+adafruit_qtpy_esp32c3.menu.CPUFreq.80.build.f_cpu=80000000L
+adafruit_qtpy_esp32c3.menu.CPUFreq.40=40MHz
+adafruit_qtpy_esp32c3.menu.CPUFreq.40.build.f_cpu=40000000L
+adafruit_qtpy_esp32c3.menu.CPUFreq.20=20MHz
+adafruit_qtpy_esp32c3.menu.CPUFreq.20.build.f_cpu=20000000L
+adafruit_qtpy_esp32c3.menu.CPUFreq.10=10MHz
+adafruit_qtpy_esp32c3.menu.CPUFreq.10.build.f_cpu=10000000L
+
+adafruit_qtpy_esp32c3.menu.FlashMode.dout=DOUT
+adafruit_qtpy_esp32c3.menu.FlashMode.dout.build.flash_mode=dout
+adafruit_qtpy_esp32c3.menu.FlashMode.dout.build.boot=dout
+adafruit_qtpy_esp32c3.menu.FlashMode.qio=QIO
+adafruit_qtpy_esp32c3.menu.FlashMode.qio.build.flash_mode=dio
+adafruit_qtpy_esp32c3.menu.FlashMode.qio.build.boot=qio
+adafruit_qtpy_esp32c3.menu.FlashMode.dio=DIO
+adafruit_qtpy_esp32c3.menu.FlashMode.dio.build.flash_mode=dio
+adafruit_qtpy_esp32c3.menu.FlashMode.dio.build.boot=dio
+adafruit_qtpy_esp32c3.menu.FlashMode.qout=QOUT
+adafruit_qtpy_esp32c3.menu.FlashMode.qout.build.flash_mode=dout
+adafruit_qtpy_esp32c3.menu.FlashMode.qout.build.boot=qout
+
+adafruit_qtpy_esp32c3.menu.FlashFreq.80=80MHz
+adafruit_qtpy_esp32c3.menu.FlashFreq.80.build.flash_freq=80m
+adafruit_qtpy_esp32c3.menu.FlashFreq.40=40MHz
+adafruit_qtpy_esp32c3.menu.FlashFreq.40.build.flash_freq=40m
+
+adafruit_qtpy_esp32c3.menu.FlashSize.4M=4MB (32Mb)
+adafruit_qtpy_esp32c3.menu.FlashSize.4M.build.flash_size=4MB
+adafruit_qtpy_esp32c3.menu.FlashSize.2M=2MB (16Mb)
+adafruit_qtpy_esp32c3.menu.FlashSize.2M.build.flash_size=2MB
+adafruit_qtpy_esp32c3.menu.FlashSize.2M.build.partitions=minimal
+
+adafruit_qtpy_esp32c3.menu.UploadSpeed.115200=115200
+adafruit_qtpy_esp32c3.menu.UploadSpeed.115200.upload.speed=115200
+adafruit_qtpy_esp32c3.menu.UploadSpeed.921600=921600
+adafruit_qtpy_esp32c3.menu.UploadSpeed.921600.upload.speed=921600
+adafruit_qtpy_esp32c3.menu.UploadSpeed.921600=921600
+adafruit_qtpy_esp32c3.menu.UploadSpeed.921600.upload.speed=921600
+adafruit_qtpy_esp32c3.menu.UploadSpeed.115200=115200
+adafruit_qtpy_esp32c3.menu.UploadSpeed.115200.upload.speed=115200
+adafruit_qtpy_esp32c3.menu.UploadSpeed.256000.windows=256000
+adafruit_qtpy_esp32c3.menu.UploadSpeed.256000.upload.speed=256000
+adafruit_qtpy_esp32c3.menu.UploadSpeed.230400.windows.upload.speed=256000
+adafruit_qtpy_esp32c3.menu.UploadSpeed.230400=230400
+adafruit_qtpy_esp32c3.menu.UploadSpeed.230400.upload.speed=230400
+adafruit_qtpy_esp32c3.menu.UploadSpeed.460800.linux=460800
+adafruit_qtpy_esp32c3.menu.UploadSpeed.460800.macosx=460800
+adafruit_qtpy_esp32c3.menu.UploadSpeed.460800.upload.speed=460800
+adafruit_qtpy_esp32c3.menu.UploadSpeed.512000.windows=512000
+adafruit_qtpy_esp32c3.menu.UploadSpeed.512000.upload.speed=512000
+
+adafruit_qtpy_esp32c3.menu.DebugLevel.none=None
+adafruit_qtpy_esp32c3.menu.DebugLevel.none.build.code_debug=0
+adafruit_qtpy_esp32c3.menu.DebugLevel.error=Error
+adafruit_qtpy_esp32c3.menu.DebugLevel.error.build.code_debug=1
+adafruit_qtpy_esp32c3.menu.DebugLevel.warn=Warn
+adafruit_qtpy_esp32c3.menu.DebugLevel.warn.build.code_debug=2
+adafruit_qtpy_esp32c3.menu.DebugLevel.info=Info
+adafruit_qtpy_esp32c3.menu.DebugLevel.info.build.code_debug=3
+adafruit_qtpy_esp32c3.menu.DebugLevel.debug=Debug
+adafruit_qtpy_esp32c3.menu.DebugLevel.debug.build.code_debug=4
+adafruit_qtpy_esp32c3.menu.DebugLevel.verbose=Verbose
+adafruit_qtpy_esp32c3.menu.DebugLevel.verbose.build.code_debug=5
+
+
+adafruit_qtpy_esp32_pico.name=Adafruit QT Py ESP32 Pico
+
+adafruit_qtpy_esp32_pico.upload.tool=esptool_py
+adafruit_qtpy_esp32_pico.upload.maximum_size=1310720
+adafruit_qtpy_esp32_pico.upload.maximum_data_size=327680
+adafruit_qtpy_esp32_pico.upload.flags=
+adafruit_qtpy_esp32_pico.upload.extra_flags=
+
+adafruit_qtpy_esp32_pico.serial.disableDTR=true
+adafruit_qtpy_esp32_pico.serial.disableRTS=true
+
+adafruit_qtpy_esp32_pico.build.tarch=xtensa
+adafruit_qtpy_esp32_pico.build.bootloader_addr=0x1000
+adafruit_qtpy_esp32_pico.build.target=esp32
+adafruit_qtpy_esp32_pico.build.mcu=esp32
+adafruit_qtpy_esp32_pico.build.core=esp32
+adafruit_qtpy_esp32_pico.build.variant=adafruit_qtpy_esp32
+adafruit_qtpy_esp32_pico.build.board=ADAFRUIT_QTPY_ESP32_PICO
+
+adafruit_qtpy_esp32_pico.build.f_cpu=240000000L
+adafruit_qtpy_esp32_pico.build.flash_size=8MB
+adafruit_qtpy_esp32_pico.build.flash_freq=80m
+adafruit_qtpy_esp32_pico.build.flash_mode=dio
+adafruit_qtpy_esp32_pico.build.boot=dio
+adafruit_qtpy_esp32_pico.build.partitions=default
+adafruit_qtpy_esp32_pico.build.defines=
+
+adafruit_qtpy_esp32_pico.menu.PartitionScheme.default=Default
+adafruit_qtpy_esp32_pico.menu.PartitionScheme.default.build.partitions=default
+adafruit_qtpy_esp32_pico.menu.PartitionScheme.no_ota=No OTA (Large APP)
+adafruit_qtpy_esp32_pico.menu.PartitionScheme.no_ota.build.partitions=no_ota
+adafruit_qtpy_esp32_pico.menu.PartitionScheme.no_ota.upload.maximum_size=2097152
+adafruit_qtpy_esp32_pico.menu.PartitionScheme.min_spiffs=Minimal SPIFFS (Large APPS with OTA)
+adafruit_qtpy_esp32_pico.menu.PartitionScheme.min_spiffs.build.partitions=min_spiffs
+adafruit_qtpy_esp32_pico.menu.PartitionScheme.min_spiffs.upload.maximum_size=1966080
+
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.921600=921600
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.921600.upload.speed=921600
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.115200=115200
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.115200.upload.speed=115200
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.256000.windows=256000
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.256000.upload.speed=256000
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.230400.windows.upload.speed=256000
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.230400=230400
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.230400.upload.speed=230400
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.460800.linux=460800
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.460800.macosx=460800
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.460800.upload.speed=460800
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.512000.windows=512000
+adafruit_qtpy_esp32_pico.menu.UploadSpeed.512000.upload.speed=512000
+
+adafruit_qtpy_esp32_pico.menu.PSRAM.enabled=Enabled
+adafruit_qtpy_esp32_pico.menu.PSRAM.enabled.build.defines=-DBOARD_HAS_PSRAM -mfix-esp32-psram-cache-issue -mfix-esp32-psram-cache-strategy=memw
+adafruit_qtpy_esp32_pico.menu.PSRAM.enabled.build.extra_libs=
+adafruit_qtpy_esp32_pico.menu.PSRAM.disabled=Disabled
+adafruit_qtpy_esp32_pico.menu.PSRAM.disabled.build.defines=
+adafruit_qtpy_esp32_pico.menu.PSRAM.disabled.build.extra_libs=
+
+adafruit_qtpy_esp32_pico.menu.DebugLevel.none=None
+adafruit_qtpy_esp32_pico.menu.DebugLevel.none.build.code_debug=0
+adafruit_qtpy_esp32_pico.menu.DebugLevel.error=Error
+adafruit_qtpy_esp32_pico.menu.DebugLevel.error.build.code_debug=1
+adafruit_qtpy_esp32_pico.menu.DebugLevel.warn=Warn
+adafruit_qtpy_esp32_pico.menu.DebugLevel.warn.build.code_debug=2
+adafruit_qtpy_esp32_pico.menu.DebugLevel.info=Info
+adafruit_qtpy_esp32_pico.menu.DebugLevel.info.build.code_debug=3
+adafruit_qtpy_esp32_pico.menu.DebugLevel.debug=Debug
+adafruit_qtpy_esp32_pico.menu.DebugLevel.debug.build.code_debug=4
+adafruit_qtpy_esp32_pico.menu.DebugLevel.verbose=Verbose
+adafruit_qtpy_esp32_pico.menu.DebugLevel.verbose.build.code_debug=5
+
+
+
+adafruit_feather_esp32_v2.name=Adafruit Feather ESP32 V2
+
+adafruit_feather_esp32_v2.upload.tool=esptool_py
+adafruit_feather_esp32_v2.upload.maximum_size=1310720
+adafruit_feather_esp32_v2.upload.maximum_data_size=327680
+adafruit_feather_esp32_v2.upload.flags=
+adafruit_feather_esp32_v2.upload.extra_flags=
+
+adafruit_feather_esp32_v2.serial.disableDTR=true
+adafruit_feather_esp32_v2.serial.disableRTS=true
+
+adafruit_feather_esp32_v2.build.tarch=xtensa
+adafruit_feather_esp32_v2.build.bootloader_addr=0x1000
+adafruit_feather_esp32_v2.build.target=esp32
+adafruit_feather_esp32_v2.build.mcu=esp32
+adafruit_feather_esp32_v2.build.core=esp32
+adafruit_feather_esp32_v2.build.variant=adafruit_feather_esp32_v2
+adafruit_feather_esp32_v2.build.board=ADAFRUIT_FEATHER_ESP32_V2
+
+adafruit_feather_esp32_v2.build.f_cpu=240000000L
+adafruit_feather_esp32_v2.build.flash_size=8MB
+adafruit_feather_esp32_v2.build.flash_freq=80m
+adafruit_feather_esp32_v2.build.flash_mode=dio
+adafruit_feather_esp32_v2.build.boot=dio
+adafruit_feather_esp32_v2.build.partitions=default
+adafruit_feather_esp32_v2.build.defines=
+
+adafruit_feather_esp32_v2.menu.PartitionScheme.default=Default
+adafruit_feather_esp32_v2.menu.PartitionScheme.default.build.partitions=default
+adafruit_feather_esp32_v2.menu.PartitionScheme.no_ota=No OTA (Large APP)
+adafruit_feather_esp32_v2.menu.PartitionScheme.no_ota.build.partitions=no_ota
+adafruit_feather_esp32_v2.menu.PartitionScheme.no_ota.upload.maximum_size=2097152
+adafruit_feather_esp32_v2.menu.PartitionScheme.min_spiffs=Minimal SPIFFS (Large APPS with OTA)
+adafruit_feather_esp32_v2.menu.PartitionScheme.min_spiffs.build.partitions=min_spiffs
+adafruit_feather_esp32_v2.menu.PartitionScheme.min_spiffs.upload.maximum_size=1966080
+
+adafruit_feather_esp32_v2.menu.UploadSpeed.921600=921600
+adafruit_feather_esp32_v2.menu.UploadSpeed.921600.upload.speed=921600
+adafruit_feather_esp32_v2.menu.UploadSpeed.115200=115200
+adafruit_feather_esp32_v2.menu.UploadSpeed.115200.upload.speed=115200
+adafruit_feather_esp32_v2.menu.UploadSpeed.256000.windows=256000
+adafruit_feather_esp32_v2.menu.UploadSpeed.256000.upload.speed=256000
+adafruit_feather_esp32_v2.menu.UploadSpeed.230400.windows.upload.speed=256000
+adafruit_feather_esp32_v2.menu.UploadSpeed.230400=230400
+adafruit_feather_esp32_v2.menu.UploadSpeed.230400.upload.speed=230400
+adafruit_feather_esp32_v2.menu.UploadSpeed.460800.linux=460800
+adafruit_feather_esp32_v2.menu.UploadSpeed.460800.macosx=460800
+adafruit_feather_esp32_v2.menu.UploadSpeed.460800.upload.speed=460800
+adafruit_feather_esp32_v2.menu.UploadSpeed.512000.windows=512000
+adafruit_feather_esp32_v2.menu.UploadSpeed.512000.upload.speed=512000
+
+adafruit_feather_esp32_v2.menu.PSRAM.enabled=Enabled
+adafruit_feather_esp32_v2.menu.PSRAM.enabled.build.defines=-DBOARD_HAS_PSRAM -mfix-esp32-psram-cache-issue -mfix-esp32-psram-cache-strategy=memw
+adafruit_feather_esp32_v2.menu.PSRAM.enabled.build.extra_libs=
+adafruit_feather_esp32_v2.menu.PSRAM.disabled=Disabled
+adafruit_feather_esp32_v2.menu.PSRAM.disabled.build.defines=
+adafruit_feather_esp32_v2.menu.PSRAM.disabled.build.extra_libs=
+
+adafruit_feather_esp32_v2.menu.DebugLevel.none=None
+adafruit_feather_esp32_v2.menu.DebugLevel.none.build.code_debug=0
+adafruit_feather_esp32_v2.menu.DebugLevel.error=Error
+adafruit_feather_esp32_v2.menu.DebugLevel.error.build.code_debug=1
+adafruit_feather_esp32_v2.menu.DebugLevel.warn=Warn
+adafruit_feather_esp32_v2.menu.DebugLevel.warn.build.code_debug=2
+adafruit_feather_esp32_v2.menu.DebugLevel.info=Info
+adafruit_feather_esp32_v2.menu.DebugLevel.info.build.code_debug=3
+adafruit_feather_esp32_v2.menu.DebugLevel.debug=Debug
+adafruit_feather_esp32_v2.menu.DebugLevel.debug.build.code_debug=4
+adafruit_feather_esp32_v2.menu.DebugLevel.verbose=Verbose
+adafruit_feather_esp32_v2.menu.DebugLevel.verbose.build.code_debug=5
+
+
+
 ##############################################################
 
 nodemcu-32s.name=NodeMCU-32S

cores/esp32/WString.cpp

@@ -774,9 +774,10 @@ void String::replace(const String& find, const String& replace) {
         }
         if(size == len())
             return;
-        if(size > capacity() && !changeBuffer(size))
+        if(size > capacity() && !changeBuffer(size)) {
             log_w("String.Replace() Insufficient space to replace string");
             return;
+        }
         int index = len() - 1;
         while(index >= 0 && (index = lastIndexOf(find, index)) >= 0) {
             readFrom = wbuffer() + index + find.len();