The BBC and Master Computer Public Domain Library

B847 INPUT#

Submitted by Steve Fewell

Description:

Call routine &BA3C to set BASIC Text Pointer B to BASIC Text Pointer A location and check that the next
character is a '#'-character. If not then generate 'Missing #' error message. Evaluate the expression after
the '#' [Type mismatch error if string value], and set Y to the number found after the '#' character (this is
the file channel number). Store the channel number to location &4C.
Call &9275 to set BASIC text pointer A offset to the BASIC text pointer B offset value (to update BASIC Text
pointer A to point to the next character on the program line after the channel number.

[&B84F] Get the next non-space character at Text pointer A location. If the next character is not a comma (','), then we
are not expecting any more data, so exit (Store Y back to &0A (Text Pointer B offset) and jump to &9002
[if the end of statement was not reached then &9002 will generate a 'Syntax Error']).

Push the channel number (&4C) to the stack.
Call &98AE to Evaluate the variable name at Text pointer A, and create the variable if it doesn't already exist.
If the zero flag is set on return from &98AE, then the text at Text pointer B was not a valid variable name, so
generate a Syntax error.
Otherwise, the variable name was valid.
Call &9275 to set BASIC text pointer A offset to the BASIC text pointer B offset value (to update BASIC Text
pointer A to point to the next character on the program line after the variable name. This is done because routine
&98AE copies Text Pointer A location to Text Pointer B location and works from Text Pointer B.
Pop the channel number from the stack abd set &4C back to the channel number.

Push the flag settings to the stack to preserve the Carry flag value after the &98AE call.
Push the IWA (variable settings) to the BASIC stack (routine &BC26).
Set Y to the channel number (&4C).
Call OSBGET (&FFD7) to get the next Variable Type byte from the data file.
Store the variable type in location &27.

Retrieve the processor flags from the Stack. If the carry flag is clear (meaning that the variable has a
numeric value - no '$' at the end) then jump to &B88A to set the Numeric variable.

Otherwise set the String variable as follows:

If the value type (&27) read from the data file is not zero (Numeric), then generate Type mismatch error as

a numeric value cannot be assigned to a String variable.

Call OSBGET (&FFD7) to get the String length & store the length in &36 (SWA length byte).

If the string length is not 0 then Call OSBGET (&FFD7) to get each character of the string value (last

character first). Store each character in the SWA (&600-&6FF) at the appropriate position (so that

&5FF + String length points to the last character of the String value).

Call &90AB to set the String variable to the SWA value (extending the length of the variable if needbe)

[or, if a memory location is being set, i.e. $&1200, then &90AB sets the required memory locations to the SWA value].

&B88A sets the numeric variable as follows:

If the value type (&27) read from the data file is zero (String), then generate Type mismatch error as

a String value cannot be assigned to a Numeric variable.

If the value type (&27) is an Integer value (&40) then call OSBGET (&FFD7) to get each byte of the

Integer value from the data file (MSB first (&2D)). Store the Integer in the IWA.

If the value type (&27) is an Float value (&FF) then call OSBGET (&FFD7) to get each byte of the packed

Floating-Point value from the data file (last byte first). Store the packed Float in Temporary Float location

&046C-&0470 and call &A539 to load the FWA with the temporary variable's value.

Call routine &BD06 to retrieve the Integer from the BASIC stack to locations &37-&3A.

This restores the variable address and type details.

Call routine &B338 to set the numeric variable. This routine will store the Numeric value (either in the

IWA or FWA) to the Numeric variable, and convert the value from Floating-Point to Integer, or vice versa,

if the variable is of a different type to the value.

Disassembly for the INPUT# routine