GS VC ACE Bootstrap source.

; 1 char: flags 1
; bit 0-1: sram bank
; bit 2: bootstrap or execute
; bit 3: specify bootstrap mail buffer scratch dest
; bit 4: base16 or hex encoding. base16 assumes little endian, hex encoding assumes big endian
; if upper 7 bits are %1110001 (- or /), execute directly. bit 4 corresponds to jump encoding
; 4 chars: bootstrap dest or execute src
; 1 char: flags 2
; bit 0: don't include header

hChecksumPrint EQU $ffe9

callw2: MACRO
    IF _NARG == 1
        call (\1 - CharPairPointerDecode) + wCmdQueue + 6 * 4
    ELSE
        call \1, (\2 - CharPairPointerDecode) + wCmdQueue + 6 * 4
    ENDC
ENDM

    callw _Bootstrap
    jp CloseSRAM

_Bootstrap::
    ld hl, wBoxNames
    ld a, [hli]
    ld b, a
    add a
    jr c, .headerNotFromMail
    push hl
    ld de, wc1d5
    push de
    callba $4, _ComposeMailMessage
    pop de
    ld a, [de]
    res 7, a
    ld [de], a
    ld b, a
    ld hl, wBoxNames
    call CopyName2
    pop hl
.headerNotFromMail
    callw2 CharPairPointerDecode
    ld h, d
    ld l, e ; hl = bootstrap dest or execute src
    ld a, b
    cp "-"
    jr c, .notDirectExecute
    jp hl
.notDirectExecute
    and $3
    bit 2, b
    jr z, .bootstrap
    call OpenSRAM
    ld a, [hli]
    ld b, a
    ld a, [hli]
    ld c, a
    ld a, [hli]
    ld d, a
    ld a, [hli]
    ld e, a
    push de ; execute dest
    jp CopyBytes ; returns into de, which is the destination
.bootstrap
    bit 3, b ; specify bootstrap buffer dest
    push af
    push de ; save dest for later
    ld de, $c755 ; default
    ld hl, wBoxNames + 9 * 2
    callw2 nz, CharPairPointerDecode
    push de
.getBootstrapCharsLoop
    push de ; push mail dest buffer
.retryMail
    ld de, wc1d5 ; temp buffer for mail message
    callba $4, _ComposeMailMessage
    pop de ; get mail dest buffer
    push de ; push mail dest buffer
    ld hl, wc1d5
    ld bc, 0
    jr .handleLoop
; hl = temp mail buffer
; de = scratch space dest
.checksumMsgLoop
    callw2 CharPairDecode
    ld [de], a
    inc de
    add c
    ld c, a
    jr nc, .handleLoop
    inc b
.handleLoop
    callw CheckNewlineChar
    ld a, [hl]
    cp "@"
    jr z, .doneChecksum
    cp "!"
    jr nz, .checksumMsgLoop
.doneChecksum
    push af ; push "!" flag
    push de ; push end of compiled message
    ld hl, hChecksumPrint + 1
    ld a, c
    ld [hld], a
    ld [hl], b
    ld d, h
    ld e, l
    coord hl, 5, 0
    lb bc, PRINTNUM_LEADINGZEROS | PRINTNUM_LEFTALIGN | 2, 5
    call PrintNum ; leftover function in GS
    call YesNoBox
    pop de ; pop end of compiled message
    pop bc ; pop flags

    jr c, .retryMail
    pop hl ; pop start of mail message (ignored)
    bit 0, b ; "@" has bit 0 set
    jr z, .getBootstrapCharsLoop
.bootstrapFinished
; perform de - hl
    pop hl
    ld a, e
    sub l
    ld c, a
    ld a, d
    sbc h
    ld b, a
    pop de ; sram dest
    pop af ; sram bank
    call OpenSRAM
    ld a, [wBoxNames + 5]
    rra
    jr c, .noHeader
    dec bc
    dec bc
    ld a, b
    ld [de], a
    inc de
    ld a, c
    ld [de], a
    inc de
    inc bc
    inc bc
.noHeader
    jp CopyBytes

CheckNewlineChar:
    ld a, [hl]
    cp $4e
    ret nz
    inc hl
    ret

; sectioned at unused space after wCmdQueue
CharPairPointerDecode:
    callw2 CharPairDecode
    ld d, a
    callw2 CharPairDecode
    ld e, a
    ret

CharPairDecode:
    push bc
    callw2 ReadAndFilterChar
    add a
    add a
    add a
    add a
    ld b, a
    callw2 ReadAndFilterChar
    and $f
    or b
    pop bc
    ret

ReadAndFilterChar:
    callw CheckNewlineChar
    ld a, [wBoxNames]
    bit 4, a
    ld a, [hli]
    ret z
    add a, 10
    ret

; event flags
; unused: d7d7 to d7ff