The BBC and Master Computer Public Domain Library

9141 PRINT#

Submitted by Steve Fewell

Description:

Copy BASIC Text pointer A values to Text Pointer B.
Check that '#' is the next non-space character - if it isn't then generate a 'Missing #' error.
Note: The next character will always be '#' as this routine is only called from the PRINT routine,
which checks for the '#' character before calling this routine!
Get the Integer value from PTR B (after the '#') and set Y to the LSB of this value.
This is the file channel number for the file that we will write to.
Push channel number to the stack.

If the next non-space character (after the channel number) is not a comma, then we have no
data to write to the file, so exit [if the end of statement was not reached then &9002 will
generate a 'Syntax Error'].

Call the expression handler (&9D3B) to obtain the result of the expression after the comma character.
Store the FWA value (in Floating-Point 5-byte packed format) to temporary Floating-Point location &046C-&0470.
This packs the FWA value (ready to be written to the file). This is done irrespective of whether the expression return
value is a Floating-Point value or not.
Retrieve the channel number (in Y) from the stack.

Store &27 (the returned value type) to the file [1-byte value] using OSBPUT (&FFD4)
[Y = channel handle & A = byte to write].

If the value type (&27) is Integer (positive &27 value) then write the 4-byte IWA value to the file
(using 4 calls to OSBPUT). The integer value is written Most-significant byte (&2D) first.

If the value type (&27) is Float (negative &27 value) then write the 5-byte packed FWA value at
location &046C-&0470 to the file (using 5 calls to OSBPUT). The Float value is written last byte (&0470) first.

If the value type (&27) is String (zero &27 value) then write the SWA value
to the file (using a separate OSBPUT call for each byte). Firstly, the string length is written (&36) [1-byte].
Next, the String value is written (last byte first (&0600+&36-1)-&0600).

After the returned value has been written, go back to &9144 to check if there are any more commas.
If another comma is present (after the expression) then another value is required to be written to the file,
so repeat the processing for the next data value. If no more values are found then goto &9187 to
pop the channel number value from the stack (clean up stack), store back the offset (in Y - set in &8EEB) to &0A
(Pointer A offset location), check for the end of statement (issuing Syntax error if not end of statement)
and start processing the next statement/program line (&9002).

Disassembly for the PRINT# routine