The BBC and Master Computer Public Domain Library

8D84 Check for Variable name character or digit (in A)

Submitted by Steve Fewell

Entry: A contains an ASCII character code.
Exit: The carry flag is 1 if the character in A is a valid variable name letter ('A'-'Z', '_', '£', 'a'-'z') or a
digit ('0'-'9'). The carry flag is 0 otherwise.

Description:

If the character (in A) is greater than or equal to 123 (&7B) then exit with Carry = 0 [char > 'z'].
If the character is greater than or equal to 95 (&5F) then exit with Carry = 1 [char = '_' or '£' or 'a'-'z'].
If the character is greater than or equal to 91 (&5B) then exit with Carry = 0 [char = '[', '\', ']' or '^'].
If the character is greater than or equal to 65 (&41) then exit with Carry = 1 [char = 'A'-'Z'].
If the character is greater than or equal to 58 (&3A) then exit with Carry = 0 [char = ':', ';', '<', '=', '>', ?' or '@'].
[&8D94] If the character is greater than or equal to 48 (&30) then exit with Carry = 1 [char = '0'-'9'].
Otherwise (if character is less than 48 (&30) then exit with Carry = 0.

Disassembly for the Check for Variable name character or digit (in A) routine