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Make Serial.print(foo, HEX) ALWAYS print 2 chars per byte #280

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Make Serial.print(foo, HEX) ALWAYS print 2 chars per byte #280

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22 changes: 19 additions & 3 deletions api/Print.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -242,11 +242,16 @@ 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';
size_t leadingZero = 0;

// prevent crash if called with base == 1
if (base < 2) base = 10;
// insert leading zero for hex values less than 0x10
else if (base == 16 && n < 16) {
write('0');
leadingZero = 1;
}

do {
char c = n % base;
Expand All @@ -255,7 +260,7 @@ size_t Print::printNumber(unsigned long n, uint8_t base)
*--str = c < 10 ? c + '0' : c + 'A' - 10;
} while(n);

return write(str);
return write(str) + leadingZero;
}

// REFERENCE IMPLEMENTATION FOR ULL
Expand Down Expand Up @@ -287,15 +292,26 @@ size_t Print::printULLNumber(unsigned long long n64, uint8_t base)
char buf[64];
uint8_t i = 0;
uint8_t innerLoops = 0;
size_t leadingZero = 0;

// Special case workaround https://github.com/arduino/ArduinoCore-API/issues/178
if (n64 == 0) {
if (base == 16) {
write('0');
write('0');
return 2;
}
write('0');
return 1;
}

// prevent crash if called with base == 1
if (base < 2) base = 10;
// insert leading zero for hex values less than 0x10
else if (base == 16 && n64 < 16) {
write('0');
leadingZero = 1;
}

// process chunks that fit in "16 bit math".
uint16_t top = 0xFFFF / base;
Expand Down Expand Up @@ -336,7 +352,7 @@ size_t Print::printULLNumber(unsigned long long n64, uint8_t base)
'0' + buf[i - 1] :
'A' + buf[i - 1] - 10));

return bytes;
return bytes + leadingZero;
}

size_t Print::printFloat(double number, int digits)
Expand Down
12 changes: 6 additions & 6 deletions test/src/Print/test_print.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -118,18 +118,18 @@ TEST_CASE ("Print::print(unsigned long long, int = DEC|HEX|OCT|BIN)", "[Print-pr
unsigned long long const val = 0;

WHEN("DEC") { mock.print(val, DEC); REQUIRE(mock._str == "0"); }
WHEN("HEX") { mock.print(val, HEX); REQUIRE(mock._str == "0"); }
WHEN("HEX") { mock.print(val, HEX); REQUIRE(mock._str == "00"); }
WHEN("OCT") { mock.print(val, OCT); REQUIRE(mock._str == "0"); }
WHEN("BIN") { mock.print(val, BIN); REQUIRE(mock._str == "0"); }
}
GIVEN("a non-zero value ...")
{
unsigned long long const val = 17;
unsigned long long const val = 15;

WHEN("DEC") { mock.print(val, DEC); REQUIRE(mock._str == "17"); }
WHEN("HEX") { mock.print(val, HEX); REQUIRE(mock._str == "11"); }
WHEN("OCT") { mock.print(val, OCT); REQUIRE(mock._str == "21"); }
WHEN("BIN") { mock.print(val, BIN); REQUIRE(mock._str == "10001"); }
WHEN("DEC") { mock.print(val, DEC); REQUIRE(mock._str == "15"); }
WHEN("HEX") { mock.print(val, HEX); REQUIRE(mock._str == "0F"); }
WHEN("OCT") { mock.print(val, OCT); REQUIRE(mock._str == "17"); }
WHEN("BIN") { mock.print(val, BIN); REQUIRE(mock._str == "1111"); }
}
}

Expand Down
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