to-uppercase.fj

// Convert lowercase ascii characters to uppercase.
// Other ascii characters are left untouched.
// Data is read from stdin and written to stdout.

  stl.startup
main:
  bit.input current_char
  bit.cmp 8, current_char, a_char, skip, continue1, continue1
continue1:
  bit.cmp 8, current_char, z_char, continue2, continue2, skip
continue2:
  bit.sub 8, current_char, to_upper
skip:
  bit.print current_char
  ;main

current_char: bit.vec 8, 0x00
to_upper: bit.vec 8, 0x20
a_char: bit.vec 8, 0x61
z_char: bit.vec 8, 0x7a