Improvements thanks to upcoming rgbds versions

[mid-kid]

This issue thread will keep track of different optimizations and improvements we can make when newer versions of rgbds are released.

These will be in some RGBDS >0.7.0:

• [ ] User-defined functions for things like coordinates (https://github.com/gbdev/rgbds/issues/201)
• [ ] Short-circuit &&/|| instead of some nested ifs

Features I think we should avoid (generally because they make it harder to process .asm files via regular expressions, as with optimize.py):

• /* block comments */
• Underscores in numeric literals
• Indented labels (except within macros) or un-indented macro usage
• Anonymous labels (not visible in the .sym file for debuggers)
• :: to separate multiple instructions on one line

[ISSOtm]

* [ ]  `ds $0150 - $0104` can become `ds $0150 - @` in home/header.asm

Well, considering hacks could choose to put anything there but 0 should be the default value for the header (as RGBFIX just patches over instead of overwriting the whole region), that'd be one of the places where ds $150 - @, 0 would make sense.

[ISSOtm]

2-arg ds added in rednex/rgbds@4cc24f436947890f41a3e16392a3c7ec7e8949ba.

[ISSOtm]

https://github.com/rednex/rgbds/releases/tag/v0.4.0

[Rangi42]

User-defined functions are under development, which will allow replacing the coord macros:

def coord(x, y) = coord(x, y, wTilemap)
def coord(x, y, origin) = y * SCREEN_WIDTH + x + origin

def bgcoord(x, y) = bgcoord(x, y, vBGMap0)
def bgcoord(x, y, origin) = y * BG_MAP_WIDTH + x + origin

Old:

    hlcoord 1, 2
    debgcoord 3, 4, wAttrmap
    dwcoord 5, 6
    ldcoord_a 7, 8
    lda_coord 9, 10

New:

    ld hl, coord(1, 2)
    ld de, bgcoord(3, 4, wAttrmap)
    dw coord(5, 6)
    ld [coord(7, 8)], a
    ld a, [coord(9, 10)]

If a ternary operator is added later, then maskbits n can become ld a, bitmask(n):

def bitmask(n) = n > 0 ? bitmask(n, 1) : 0
def bitmask(n, x) = n <= x+1 ? x : bitmask(n, x*2+1)

[ISSOtm]

Features I think we should avoid (generally because they make it harder to process .asm files via regular expressions, as with optimize.py):

* New `MACRO name` and `DEF name EQU value` syntax (the old syntaxes are more familiar and not deprecated)

Be careful, as the changelog states:

The old syntax will still be supported for a couple versions, but may eventually be phased out.

(Emphasis added.) The syntax change is to get rid of the newbie trap that is "column 1", and it hasn't been deprecated as a courtesy due to the wide usage; but you're still strongly advised to prepare for an eventual deprecation.

[Rangi42]

def rgb555(r, g, b) = (r << 0) | (g << 5) | (b << 10)

RGB: MACRO
rept _NARG / 3
    assert_valid_rgb \1, \2, \3
    dw rgb555(\1, \2, \3)
    shift 3
endr
ENDM

[Rangi42]

BASE_TMHM rb (NUM_TM_HM_TUTOR + 7) / 8
for n, (NUM_TM_HM_TUTOR + 7) / 8
    ds ((\1) + 7) / 8

def nb_flags(n) := (n + 7) / 8

BASE_TMHM rb nb_flags(NUM_TM_HM_TUTOR)
for n, nb_flags(NUM_TM_HM_TUTOR)
    ds nb_flags(\1)

[rawr51919]

This issue I presume is meant to be a tracker for RGBDS updates and the syntax that goes along with them for pokecrystal adoption