GCC HOME: C:\Program Files (x86)\GNU Tools ARM Embedded\5.2 2015q4\bin
compile:
    [mkdir] Created dir: C:\CooCox\CoIDE\workspace\MegaProj\megaproj\Debug\bin
    [mkdir] Created dir: C:\CooCox\CoIDE\workspace\MegaProj\megaproj\Debug\obj
       [cc] 10 total files to be compiled.
       [cc] arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -Wall -ffunction-sections -g -O0 -c -DSTM32F407VG -DSTM32F4XX -DUSE_STDPERIPH_DRIVER -D__ASSEMBLY__ -IC:\CooCox\CoIDE\workspace\MegaProj\cmsis_lib\include -IC:\CooCox\CoIDE\workspace\MegaProj\cmsis_lib -IC:\CooCox\CoIDE\workspace\MegaProj\cmsis -IC:\CooCox\CoIDE\workspace\MegaProj -IC:\CooCox\CoIDE\workspace -IC:\CooCox\CoIDE\workspace\MegaProj\semihosting -IC:\CooCox\CoIDE\workspace\MegaProj\cmsis_boot C:\CooCox\CoIDE\workspace\MegaProj\semihosting\semihosting.c C:\CooCox\CoIDE\workspace\MegaProj\cmsis_lib\source\stm32f4xx_usart.c C:\CooCox\CoIDE\workspace\MegaProj\cmsis_boot\startup\startup_stm32f4xx.c C:\CooCox\CoIDE\workspace\MegaProj\main.c C:\CooCox\CoIDE\workspace\MegaProj\cmsis_lib\source\stm32f4xx_rcc.c C:\CooCox\CoIDE\workspace\MegaProj\stdio\printf.c C:\CooCox\CoIDE\workspace\MegaProj\cmsis_lib\source\stm32f4xx_gpio.c C:\CooCox\CoIDE\workspace\MegaProj\semihosting\sh_cmd.s C:\CooCox\CoIDE\workspace\MegaProj\cmsis_boot\system_stm32f4xx.c C:\CooCox\CoIDE\workspace\MegaProj\syscalls\syscalls.c
       [cc] C:\CooCox\CoIDE\workspace\MegaProj\semihosting\semihosting.c:27:7: warning: array subscript has type 'char' [-Wchar-subscripts]
       [cc] C:\CooCox\CoIDE\workspace\MegaProj\semihosting\semihosting.c: In function 'SH_SendChar':
       [cc]   g_buf[g_buf_len++] = ch;
       [cc]        ^
       [cc] C:\CooCox\CoIDE\workspace\MegaProj\semihosting\semihosting.c:28:7: warning: array subscript has type 'char' [-Wchar-subscripts]
       [cc]   g_buf[g_buf_len] = '\0';
       [cc]        ^
       [cc] C:\CooCox\CoIDE\workspace\MegaProj\semihosting\semihosting.c: In function 'SH_SendString':
       [cc] C:\CooCox\CoIDE\workspace\MegaProj\semihosting\semihosting.c:47:6: warning: unused variable 'j' [-Wunused-variable]
       [cc]   int j;
       [cc]       ^
       [cc] Starting link
       [cc] arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -g -nostartfiles -Wl,-Map=MegaProj.map -O0 -Wl,--gc-sections -LC:\CooCox\CoIDE\configuration\ProgramData\MegaProj -Wl,-TC:\CooCox\CoIDE\configuration\ProgramData\MegaProj/arm-gcc-link.ld -g -o MegaProj.elf ..\obj\semihosting.o ..\obj\stm32f4xx_usart.o ..\obj\startup_stm32f4xx.o ..\obj\main.o ..\obj\stm32f4xx_rcc.o ..\obj\printf.o ..\obj\stm32f4xx_gpio.o ..\obj\sh_cmd.o ..\obj\system_stm32f4xx.o ..\obj\syscalls.o
       [cc] c:/program files (x86)/gnu tools arm embedded/5.2 2015q4/bin/../lib/gcc/arm-none-eabi/5.2.1/../../../../arm-none-eabi/lib/armv7e-m\libg.a(lib_a-impure.o):(.data._impure_ptr+0x0): multiple definition of `_impure_ptr'
       [cc] ..\obj\printf.o:(.data+0x428): first defined here
       [cc] collect2.exe: error: ld returned 1 exit status

BUILD FAILED
Total time: 2 seconds

#include <stdio.h>
#include <stm32f4xx_gpio.h>
#include <stm32f4xx_rcc.h>

const char* terminator = "                \r\n"; // More than 16 symbols to overload the buffer ^_^

int main(void)
{

//    setbuf(stdout, NULL);


    printf("Hello World!%s", terminator);
//    fflush(stdout);

    while(1)
    {
        printf("Oy vey!%s", terminator);
        fflush(stdout);
    }
}

void PrintChar(char c)
{
    SH_SendChar(c);
}

static char g_buf[16];
static char g_buf_len = 0;
...
void SH_SendChar(int ch) {
    g_buf[g_buf_len++] = ch;
    g_buf[g_buf_len] = '\0';
    if (g_buf_len + 1 >= sizeof(g_buf) || ch == '\n' || ch == '\0') {
        g_buf_len = 0;
        /* Send the char */
        if (SH_DoCommand(0x04, (int) g_buf, NULL) != 0) {
            return;
        }
    }
}