##### How to build Mandarin Voice #####
1. jni/jni/EkhoService.cpp about line 223, change to gp_ekho->setVoice("Mandarin");
2. res/raw/ekhodata.zip->Cantonese files(.dict/.voice/.index) replace with linux ekho-9.0.tar.xz->Mandarin files(.dict/.voice/.index)
3. change applicationId in build.gradle
4. change app_name in res/values/donottranslate.xml
5. change icon
6. change CheckVoiceData.java
$ git diff src/net/eguidedog/ekho/CheckVoiceData.java
diff --git a/src/net/eguidedog/ekho/CheckVoiceData.java b/src/net/eguidedog/ekho/CheckVoiceData.java
index 1d62312..8789756 100644
--- a/src/net/eguidedog/ekho/CheckVoiceData.java
+++ b/src/net/eguidedog/ekho/CheckVoiceData.java
@@ -47,9 +47,12 @@ public class CheckVoiceData extends Activity {

     /** Resources required for Ekho to run correctly. */
     private static final String[] BASE_RESOURCES = {
-        "zhy.dict",
-        "jyutping.index",
-        "jyutping.voice",
+            "zh.dict",
+            "pinyin.index",
+            "pinyin.voice",
+        //"zhy.dict",
+        //"jyutping.index",
+        //"jyutping.voice",
     };

     public static File getDataPath(Context context) {

##### How to build #####
1. open project with Android Studio.
2. ndk-build V=1

##### Build eSpeak NG Android project #####
1. get code and build from https://github.com/espeak-ng/espeak-ng/tree/master/android
2. fix checksum plugin issue: https://plugins.gradle.org/plugin/org.gradle.crypto.checksum
3. copy espeak-ng-data from a relase version

##### support English #####
see jni/flite_diff

Flite latest source: https://github.com/festvox/flite
Flite home page: http://www.festvox.org/flite/
build systems: https://developer.android.com/ndk/guides/other_build_systems

git clone https://github.com/festvox/flite
cd flite

./configure --with-langvox=android --target=arm64-androidmake
link arm64-v8a-android -> aarch64-android in flite/build
change config/config
make

./configure --with-langvox=android --target=arm-android
link armeabi-v7a-android -> arm-android in flite/build
change config/config
make

./configure --with-langvox=android --target=x86-android
change config/config
make

./configure --with-langvox=android --target=x86_64-android
change config/config
make

change compiler in flite/config/config for x86-android:
CC       = /Users/hgneng/Library/Android/sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/darwin-x86_64/bin/clang++
CFLAGS   = -g -O2 -Wall -fpic -O3 -DANDROID --sysroot=/Users/hgneng/Library/Android/sdk/ndk/21.4.7075529/sysroot -I/Users/hgneng/Library/Android/sdk/ndk/21.4.7075529/sysroot/usr/include/i686-linux-android
AR       = /Users/hgneng/Library/Android/sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/darwin-x86_64/bin/i686-linux-android-ar
RANLIB   = /Users/hgneng/Library/Android/sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/darwin-x86_64/bin/i686-linux-android-ranlib

##### Troubleshooting #####

We may need to fix atof with strtod.

We may need to upgrade Android API to 21 (minSdkVersion in build.gradle and APP_PLATFORM := android-21 in Application.mk) to fix undefined reference 'rand' issue. (refer to https://stackoverflow.com/questions/66455212/android-ndk-returns-an-error-undefined-reference-to-rand-srand)

We may need to use nm to check flite.a to debug undefined reference issue. Sometimes, we use C++ compiler to build flite will cause undefined reference issue. Symbols may be stripped in some so file in order to reduce size.

g721_encoder g721_decoder exists both in flite and libsndfile. Need to rename them in flite in case of conflict.

After modifying libs, we need to make some changes in EkhoService.cpp to trigger re-link the libs and generate a new libttsekho.so.

##### flite diff #####
~/code/ekho-android-cantonese/jni/flite$ git diff
diff --git a/config/android.lv b/config/android.lv
index ff5422e..19dc4db 100644
--- a/config/android.lv
+++ b/config/android.lv
@@ -1,5 +1,8 @@
 #
 #  The base languages, lexicons and voices
-LEXES += cmulex cmu_indic_lang
-LANGS += usenglish cmu_indic_lex
+#LEXES += cmulex cmu_indic_lang
+LEXES += cmulex
+#LANGS += usenglish cmu_indic_lex
+LANGS += usenglish
 #VOXES += cmu_us_generic_cg
+VOXES += cmu_us_kal
diff --git a/src/utils/cst_string.c b/src/utils/cst_string.c
index 38bc5f3..1242b36 100644
--- a/src/utils/cst_string.c
+++ b/src/utils/cst_string.c
@@ -74,7 +74,8 @@ cst_string *cst_strrchr(const cst_string *str, int c)

 double cst_atof(const char *str)
 {
-    return atof(str);
+    char* endPtr;
+    return strtod(str, &endPtr);
 }
 #endif /* WinCE */

ekho-android-cantonese/jni/flite$ git diff
diff --git a/src/speech/cst_wave_utils.c b/src/speech/cst_wave_utils.c
index c69066e..ef11c5f 100644
--- a/src/speech/cst_wave_utils.c
+++ b/src/speech/cst_wave_utils.c
@@ -163,7 +163,7 @@ unsigned char *cst_g721_decode(int *actual_size,int size,
             code = (xcode & 0xF0) >> dec_bits;
         else
             code = (xcode & 0x0F);
-        sample_short = g721_decoder(code,AUDIO_ENCODING_LINEAR,&state);
+        sample_short = flite_g721_decoder(code,AUDIO_ENCODING_LINEAR,&state);
         unpacked_residual[ur] = cst_short_to_ulaw(sample_short);
     }

diff --git a/src/speech/g721.c b/src/speech/g721.c
index d1cec7b..e51efd4 100644
--- a/src/speech/g721.c
+++ b/src/speech/g721.c
@@ -115,7 +115,7 @@ static short        _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
  * the resulting code. -1 is returned for unknown input coding value.
  */
 int
-g721_encoder(
+flite_g721_encoder(
        int             sl,
        int             in_coding,
        struct g72x_state *state_ptr)
@@ -166,7 +166,7 @@ g721_encoder(
  * return -1 for unknown out_coding value.
  */
 int
-g721_decoder(
+flite_g721_decoder(
        int             i,
        int             out_coding,
        struct g72x_state *state_ptr)
diff --git a/src/speech/g72x.h b/src/speech/g72x.h
index ab18d8e..17759b4 100644
--- a/src/speech/g72x.h
+++ b/src/speech/g72x.h
@@ -118,11 +118,11 @@ struct g72x_state {
 /* External function definitions. */

 extern void g72x_init_state(struct g72x_state *);
-extern int g721_encoder(
+extern int flite_g721_encoder(
                int sample,
                int in_coding,
                struct g72x_state *state_ptr);
-extern int g721_decoder(
+extern int flite_g721_decoder(
                int code,
                int out_coding,
                struct g72x_state *state_ptr);