; stdio.h -- Standard interface definitons for the Hawk monitor I/O support.
;   Linkage conventions:
;     R1 -- used for linkage by all support routines.
;     R2 -- typically used internally as an activation record pointer.
;     R3 -- typically the first parameter and function return value
;     R4 -- typically the second parameter, if there is one.

;-------------------------------
; linkage to monitor display management routines

	EXT	PUTAT	; set display text coordinates
			;   takes R3=column/X R4=row/Y (origin in top left)
			;   wipes out R3-7
			;   uses 3 words of stack
			;   C equivalent: none

	EXT	PUTCHAR	; output one character
			;   takes R3=character
			;   wipes out R4-5
			;   uses 1-3 words of stack
			;   C equivalent: putchar(ch)

	EXT	PUTS	; output one null terminated string (std C, adds LF)
			;   takes R3=string pointer
			;   wipes out R3-7
			;   calls PUTCHAR (which uses 1-3 words of stack)
			;   C equivalent: puts(string)

	EXT	PUTSTR	; output one null terminated string (without LF)
			;   takes R3=string pointer
			;   wipes out R3-7
			;   calls PUTCHAR (which uses 1-3 words of stack)
			;   C equivalent: fputs(string,stdout)

	EXT	PUTHEX	; output integer in hexadecimal
			;   takes R3=integer to print
			;   takes R4=field width
			;   wipes out R3-7
			;   uses 3 words of stack
			;   calls PUTCHAR (which uses 1-3 words of stack)
			;   C equivalent: printf("%*X",width,integer)

	EXT	PUTDEC	; output signed integer in decimal
	EXT	PUTDECU	; output unsigned integer in decimal
			;   takes R3=integer to print
			;   takes R4=field width
			;   wipes out R3-6
			;   uses up to 11 words of stack (recursively)
			;   calls PUTCHAR (which uses 3 words of stack)
			;   C equivalent: printf("%*d",width,integer)
			;   C equivalent: printf("%*u",width,integer)

;-------------------------------
; linkage to monitor keyboard interface

	EXT	GETCHAR	; get a character from the keyboard (std C)
			;   returns R3=character
			;   wipes out R4

	EXT	GETS	; get null-terminated string from keyboard (std C)
			;   takes R3=pointer to string buffer
			;   wipes out R3-7
			;   calls PUTCHAR (which uses 3 words of stack)
			;   calls GETCHAR (which uses 3 words of stack)

;-------------------------------
; linkage to monitor terminal description

	EXT	TERMINFO; a global structure with two fields
TERMROWS=	0	; the number of rows on the screen (height)
TERMCOLS=	4	; the number of columns on the screen (height)

;-------------------------------
; strange accident that NULL is defined here
NULL	=	0