Standard Input/Output Functions for Apple 1

At the beginning of the program use the directives

  #include <stdioh02>
  
The following functions are defined:

  c = getchr();       Waits for a keypress and returns the cleaned 
                      ASCII value corresponding to the pressed key.
                      
                      Note: Calls getkey() from system library.

  putchr(c);          Writes character c to the screen.
                      
                      Note: Calls prchr() from system library.

  r = getstr(&s);     Reads a maximum of 128 characters from keyboard 
                      until the Return/Enter key is pressed, storing the 
                      entered characters as null-terminated string s.
                      
                      Allows corrections using Backspace/Delete. 
                      
                      Pressing the Escape/Abort key terminates entry,
                      leaving the string in an undefined state.
                      
                      Returns number of characters entered, or 255
                      if entry was aborted.

                      Note: Calls getchr() in a loop and uses constants 
                      DELKEY, RTNKEY, and ESCKEY from the system library.

  r = outstr(&s):     Writes up to 128 characters of null-terminated 
                      string s to the screen.
                      
                      Returns position of null terminator in string.
                      
                      Note: Calls outsub(0, &s).

  r = outsub(n, &s):  Writes up to 128 characters of null-terminated 
                      string s to the screen, starting at position n.
                      
                      Returns position of null terminator in string.
                      
                      Note: Calls putchr() in a loop.

  r = putstr(&s):     Writes up to 128 characters of null-terminated 
                      string s to the screen and advances the cursor to 
                      the beginning of the next line.
                    
                      Returns number of characters printed.
                    
                      Note: Calls outstr(&s) followed by newlin().

Note: This library expects the following functions to be defined:

  getkey();         Wait for and read ASCII character from keyboard
  prchr();          Print ASCII character to screen
  delchr();         Backspace and delete previous character on screen
  newlin();         Advance cursor to beginning of next line

along with the sequential Zero Page locations
  
  strlo:            String Pointer (low byte)             
  strhi:            String Pointer (high byte)

and the assembler constants
  
  DELKEY            Delete/Backspace key ASCII code (usually DEL or BS)
  ESCKEY            Escape/Abort key ASCII code (usually ESC)
  RTNKEY            Return/Enter key ASCII code (usually CR)