Add __CYCLES__ variable to count cycles used by instructions (#2171)

test/asm/cycles.asm

@@ -0,0 +1,63 @@
+assert !def(__CYCLES__)
+
+SECTION "test", ROM0
+assert def(__CYCLES__)
+
+assert __CYCLES__ == 0
+nop
+assert __CYCLES__ == 1
+ld a, 42
+assert __CYCLES__ == 3
+dec a
+assert __CYCLES__ == 4
+db $c9
+assert __CYCLES__ == 4 ; data does not increment __CYCLES__
+
+PUSHS
+assert !def(__CYCLES__)
+
+SECTION FRAGMENT "fragmented", ROM0
+assert def(__CYCLES__)
+
+assert __CYCLES__ == 0
+add [hl]
+assert __CYCLES__ == 2
+add b
+assert __CYCLES__ == 3
+
+DEF __CYCLES__ = 1
+assert __CYCLES__ == 1
+ccf
+assert __CYCLES__ == 2
+
+POPS
+assert __CYCLES__ == 4
+
+SECTION UNION "united", WRAM0
+assert __CYCLES__ == 0
+DEF __CYCLES__ = 42
+assert __CYCLES__ == 42
+
+SECTION FRAGMENT "fragmented", ROM0
+assert __CYCLES__ == 2 ; this fragment continues from the previous one
+
+SECTION UNION "united", WRAM0
+assert __CYCLES__ == 42 ; this union continues from the previous one
+
+SECTION "rom code", ROM0
+assert __CYCLES__ == 0
+ld hl, STARTOF("ram code")
+assert __CYCLES__ == 3
+
+LOAD "ram code", HRAM
+assert __CYCLES__ == 0
+ld hl, @
+assert __CYCLES__ == 3
+inc hl
+assert __CYCLES__ == 5
+
+ENDL
+assert __CYCLES__ == 3
+
+ENDSECTION
+assert !def(__CYCLES)