cc65/libsrc/cbm/exehdr.s

;
; Ullrich von Bassewitz, 2010-11-14
;
; This module supplies a small BASIC stub program that jumps to the machine
; language code that follows it using SYS.
;

        ; The following symbol is used by linker config to force the module
        ; to get included into the output file
        .export         __EXEHDR__: absolute = 1

.segment        "EXEHDR"

        .addr   Next
        .word   .version        ; Line number
        .byte   $9E             ; SYS token
;       .byte   <(((Start / 10000) .mod 10) + '0')
        .byte   <(((Start /  1000) .mod 10) + '0')
        .byte   <(((Start /   100) .mod 10) + '0')
        .byte   <(((Start /    10) .mod 10) + '0')
        .byte   <(((Start /     1) .mod 10) + '0')
        .byte   $00             ; End of BASIC line
Next:   .word   0               ; BASIC end marker
Start:

; If the start address is larger than 4 digits, the header generated above
; will not contain the highest digit. Instead of wasting one more digit that
; is almost never used, check it at link time and generate an error so the
; user knows something is wrong.

.assert (Start < 10000), error, "Start address too large for generated BASIC stub"