sprocket-device-illucat/lib/sprocket-utils/utils_print.cpp

#include "utils_print.h"

int FORMAT_BUFFER_SIZE(const char* format, ...) {
    va_list args;
    va_start(args, format);
    int result = vsnprintf(NULL, 0, format, args);
    va_end(args);
    return result + 1; // safe byte for \0
}
void PRINT_MSG(Print &out, const char* prefix, const char* format, ...) {
    if(SPROCKET_PRINT){
        out.print(String(prefix) + String(": "));
        char formatString[128], *ptr;
        strncpy_P( formatString, format, sizeof(formatString) ); // copy in from program mem
        // null terminate - leave last char since we might need it in worst case for result's \0
        formatString[ sizeof(formatString)-2 ]='\0'; 
        ptr=&formatString[ strlen(formatString)+1 ]; // our result buffer...
        va_list args;
        va_start (args,format);
        vsnprintf(ptr, sizeof(formatString)-1-strlen(formatString), formatString, args );
        va_end (args);
        formatString[ sizeof(formatString)-1 ]='\0'; 
        out.print(ptr);
    }
}