fix compile printf bug

cores/arduino/Print.cpp

@@ -274,6 +274,24 @@ size_t Print::printFloat(double number, uint8_t digits)
     return n;
 }
 
+extern "C" {
+  __attribute__((weak))
+  int _write(int file, char *ptr, int len)
+  {
+    switch (file) {
+      case STDOUT_FILENO:
+      case STDERR_FILENO:
+        break;
+      case STDIN_FILENO:
+        break;
+      default:
+        ((class Print *)file)->write((uint8_t *)ptr, len);
+        break;
+    }
+    return len;
+  }
+}
+
 int Print::printf (const char *__restrict __format, ...)
 {
     char printf_buff[PRINT_PRINTF_BUFFER_LENGTH];

cores/arduino/libcore/syscalls.c

@@ -13,7 +13,6 @@
 #undef errno
 extern int errno;
 
-extern size_t uart_debug_write(uint8_t *data, uint32_t size);
 
 // Helper macro to mark unused parameters and prevent compiler warnings.
 // Appends _UNUSED to the variable name to prevent accidentally using them.

package_at32_index.json

@@ -12,7 +12,7 @@
         {
           "name": "AT32F403ACGU7 Core Board",
           "architecture": "at32f403a",
-          "version": "0.0.2",
+          "version": "0.0.3",
           "category": "Contributed",
           "url": "https://github.com/WeActStudio/ArduinoCore-AT32F4/archive/refs/heads/main.zip",
           "archiveFileName": "ArduinoCore-AT32F4-main.zip",

platform.txt

@@ -21,12 +21,13 @@ compiler.size.cmd=arm-none-eabi-size
 ##Set the compiler flags
 compiler.ar.flags=rcs
 compiler.asm.flags=-mthumb -Wall -g -Os 
-compiler.c.flags=-mthumb -Wall -std=gnu11 -ffunction-sections -g -Os -fno-exceptions
-compiler.cpp.flags=-mthumb -Wall -std=gnu++11 -ffunction-sections -g -Os -fno-exceptions -fno-rtti
-compiler.elf.flags=-mthumb -g -Wl,--gc-sections -Wall --specs=nano.specs -lstdc++ -lm
+compiler.c.flags=-mthumb -Wall -MMD -std=gnu11 -ffunction-sections -g -Os -fno-exceptions
+compiler.cpp.flags=-mthumb -Wall -MMD -std=gnu++11 -ffunction-sections -g -Os -fno-exceptions -fno-rtti
+compiler.elf.flags=-mthumb -g -Wl,--gc-sections -Wall -lstdc++ -lm
 compiler.hex.flags=-Oihex
 compiler.bin.flags=-Obinary
-
+compiler.combine.flags=-u _printf_float -u _sbrk -u link -u _close -u _fstat -u _isatty -u _lseek -u _read -u _write -u _exit -u kill -u _getpid
+compiler.c.elf.extra_flags="-L{build.variant.path}/ld" -specs=nosys.specs -specs=nano.specs {compiler.combine.flags}
 build.common_flags=-mthumb
 
 ##===============================================##
@@ -44,7 +45,7 @@ recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -m
 
 recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} "{archive_file_path}" "{object_file}"
 
-recipe.c.combine.pattern="{compiler.path}{compiler.elf.cmd}" {compiler.elf.flags} -mcpu={build.mcu} "-L{build.variant.path}" "-T{build.variant.path}/{build.ldscript}" {object_files} "{archive_file_path}" "{build.variant.path}/{build.variant_system_lib}" -o "{build.path}/{build.project_name}.elf"
+recipe.c.combine.pattern="{compiler.path}{compiler.elf.cmd}" {compiler.elf.flags} -mcpu={build.mcu} "-L{build.variant.path}" "-T{build.variant.path}/{build.ldscript}" {object_files} "{archive_file_path}" "{build.variant.path}/{build.variant_system_lib}" {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf"
 ##recipe.c.combine.pattern="{compiler.path}{compiler.elf.cmd}" {compiler.elf.flags} -mcpu={build.mcu} "-T{build.variant.path}/{build.ldscript}" "-Wl,-Map,{build.path}/{build.project_name}.map" -o "{build.path}/{build.project_name}.elf" "-L{build.path}" -lm -lgcc -mthumb -Wl,--cref -Wl,--check-sections -Wl,--gc-sections -Wl,--unresolved-symbols=report-all -Wl,--warn-common -Wl,--warn-section-align -Wl,--warn-unresolved-symbols -Wl,--start-group {object_files} -Wl,--whole-archive "{archive_file_path}" -Wl,--no-whole-archive -Wl,--end-group
 
 recipe.objcopy.eep.pattern=