diff --git a/cores/arduino/Print.cpp b/cores/arduino/Print.cpp index 1e4c99a65..efca8c2be 100644 --- a/cores/arduino/Print.cpp +++ b/cores/arduino/Print.cpp @@ -202,22 +202,101 @@ size_t Print::println(const Printable& x) size_t Print::printNumber(unsigned long n, uint8_t base) { - char buf[8 * sizeof(long) + 1]; // Assumes 8-bit chars plus zero byte. - char *str = &buf[sizeof(buf) - 1]; - - *str = '\0'; + // shortcut printing just 0 and prevent later overhead + if (n == 0) { + return write('0'); + } // prevent crash if called with base == 1 - if (base < 2) base = 10; - - do { - char c = n % base; - n /= base; - - *--str = c < 10 ? c + '0' : c + 'A' - 10; - } while(n); - - return write(str); + if (base < 2) return printNumber(n, 10); + +// use -D ARDUINO_PRINT_NUMBER_GENERIC_ONLY when compiling to get only the generic version +#ifndef ARDUINO_PRINT_NUMBER_GENERIC_ONLY + switch (base) { + case 16: + // optimized version for hex prints + { + uint8_t *access = (uint8_t*) &n; + uint8_t written = 0; + for (int8_t i=sizeof(unsigned long)-1; i>=0; i--) { + char c; + c = (access[i] & 0xf0) >> 4; + if (c != 0 || written != 0) { + c = (c < 10 ? c + '0' : c + 'A' - 10); + written += write(c); + } // else: skip leading zeros + c = access[i] & 0x0f; + if (c != 0 || written != 0) { + c = (c < 10 ? c + '0' : c + 'A' - 10); + written += write(c); + } // else: skip leading zeros + } + return written; + } + case 2: + // optimized version for binary prints + { + uint8_t *access = (uint8_t*) &n; + uint8_t written = 0; + for (int8_t i=sizeof(unsigned long)-1; i>=0; i--) { + if (access[i] == 0 && written == 0) { + // skip leading zeros + continue; + } + for (int8_t j=7; j>=0; j--) { + char c; + if (j == 0) { + // avoid shift by 0 - undefined + c = (access[i] & 0x01); + } else { + c = (access[i] & 1<> j; + } + if (c == 0 && written == 0) { + // skip leading zeros + continue; + } + c = (c < 10 ? c + '0' : c + 'A' - 10); + written += write(c); + } + } + return written; + } + default: + // the generic implementation +#endif + { + unsigned long reverse = 0; + uint8_t digits = 0; + char avoid_overflow = n % base; + + // this step and 'avoid_overflow' will make sure it stays in unsigned long range being able to print all 10 digits no matter what + n /= base; + + // reverse the number and count digits + while (n != 0) { + uint8_t remainder = n % base; + reverse = reverse * base + remainder; + n /= base; + digits++; + } + + // from here onwards reuse of variable 'n' to count written chars + while (digits--) { + char c = reverse % base; + reverse /= base; + + c = (c < 10 ? c + '0' : c + 'A' - 10); + n += write(c); + } + + avoid_overflow = (avoid_overflow < 10 ? avoid_overflow + '0' : avoid_overflow + 'A' - 10); + n += write(avoid_overflow); + + return n; + } +#ifndef ARDUINO_PRINT_NUMBER_GENERIC_ONLY + } +#endif } size_t Print::printFloat(double number, uint8_t digits) pFad - Phonifier reborn

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