Comment by Joker_vD
But this is not what's the code doing, is it? It's not doing (ch & 0x7F), it's doing ch <= 0x7F. And the parity checking/filtering is done in the tape drive/serial port driver anyhow, it would never reach wc in the first place.
But this is not what's the code doing, is it? It's not doing (ch & 0x7F), it's doing ch <= 0x7F. And the parity checking/filtering is done in the tape drive/serial port driver anyhow, it would never reach wc in the first place.
Yes, that's true for that code. But that wasn't really the point, the point I wrote in my earlier post was that ASCII is 7 bits, it's 0..127, and, depending on where the characters came from, only values below 128 are valid ASCII. What I was talking about was that because a parity bit was common, ASCII was limited to 7 bits, to make room for a parity bit. When other transports are involved, e.g. reading from a file, there aren't any parity bits (well, that's not entirely true - a minicomputer I worked with back in the day used parity bits on characters in text files, but that's not the case for the platform where this particular old 'wc' was used), the code simply focuses on valid ASCII, which is below 128.