in src/uuid_string.c [22:51]
static bool isHexDigit(char c, uint8_t* value)
{
int result;
if (('0' <= c) && (c <= '9'))
{
*value = c - '0';
result = true;
}
else
{
if (('a' <= c) && (c <= 'f'))
{
*value = 0xA + c - 'a';
result = true;
}
else
{
if (('A' <= c) && (c <= 'F'))
{
*value = 0xA + c - 'A';
result = true;
}
else
{
result = false;
}
}
}
return result;
}