; E01-S05: capacity-checking skeleton for cfg/compiler.cfg.
;
; Links the production src/compiler/mmu.s with the frozen memory map and
; proves, in x128, every region and rule the compiler will depend on. Results
; go to the fixed test mailbox (src/common/mailbox.inc):
;   MB_STATUS  $A5 pass / $FA fail
;   MB_CODE    16-bit mask of FAILED checks (CHECK_*), 0 on pass
;   MB_DATA+0  NMIs counted by mmu_nmi_guard
;   MB_DATA+1  CR seen right after the NMI (expect $4E)
;   MB_DATA+2  P0L seen right after the NMI (expect the private page)
;   MB_DATA+3  private zero-page sentinel after the NMI (expect $C5)
;
; Assemble with -D OVERFLOW_<REGION>=1 to prove ld65 rejects an overflow of
; ZP, COMMON, MAIN, SWSTACK, or TABLES.

.setcpu "6502"
.include "../../src/common/c128.inc"
.include "../../src/common/mailbox.inc"

.import mmu_init, mmu_bank0, mmu_bank1, mmu_system, mmu_shutdown
.import mmu_peek1, mmu_poke1, kcall_inline, mmu_nmi_count
.importzp mmu_ptr
.import __COMPILER_ZP_PAGE__

CHECK_ZP      = $0001             ; private zero page isolated from system ZP
CHECK_KCALL   = $0002             ; KERNAL calls from both states keep ZP/MMU
CHECK_BANK1   = $0004             ; first/last table bytes are bank-1 only
CHECK_NMI     = $0008             ; NMI under bank 1 + private ZP is harmless
CHECK_COMMON  = $0010             ; COMMON/DISKBUF/SCRATCH/MAILBOX shared
CHECK_RESTORE = $0020             ; exact system state after mmu_shutdown
CHECK_ALL     = $003F

ZP_SENTINEL   = $C5

.segment "LOADADDR"
        .word $1C01

.segment "EXEHDR"
        .word basic_end
        .word 10
        .byte $9E
        .byte "7181"              ; SYS $1C0D
        .byte $00
basic_end:
        .word $0000

.segment "ZEROPAGE"
zp_probe:       .res 1
.ifdef OVERFLOW_ZP
                .res $FE
.endif

.segment "MAILBOX"
mailbox:        .res MB_SIZE
.assert mailbox = MB_BASE, error, "MAILBOX segment must sit at MB_BASE"

.segment "DISKBUF"
diskbuf:        .res $100

.segment "SCRATCH"
scratch:        .res 1

.segment "SWSTACK"
swstack_first:  .res 1
                .res $0800 - 2
swstack_last:   .res 1
.ifdef OVERFLOW_SWSTACK
                .res 1
.endif

.segment "TABLES"
tables_first:   .res 1
                .res $5500 - 2
tables_last:    .res 1
.ifdef OVERFLOW_TABLES
                .res 1
.endif

; --------------------------------------------------------------- STARTUP
.segment "STARTUP"
.export skel_entry
skel_entry:
        php
        sei
        tsx
        stx entry_sp

        ldx #MB_SIZE - 1           ; mailbox: initialized and running
        lda #$00
@clr:   sta MB_BASE,x
        dex
        bpl @clr
        lda #MB_MAGIC0_VALUE
        sta MB_MAGIC0
        lda #MB_MAGIC1_VALUE
        sta MB_MAGIC1
        lda #MB_PROD_PLATFORM
        sta MB_PRODUCER
        lda #MB_ST_RUNNING
        sta MB_STATUS
        lda #<CHECK_ALL            ; every check starts failed
        sta fail_mask
        lda #>CHECK_ALL
        sta fail_mask+1

        lda MMU_CR                 ; system state for CHECK_RESTORE
        sta entry_state+0
        ldx #4
@save:  lda MMU_RCR,x
        sta entry_state+1,x
        dex
        bpl @save
        lda NMINV
        sta entry_state+6
        lda NMINV+1
        sta entry_state+7
        lda zp_probe               ; system ZP byte at the probe's offset
        sta sys_zp_before

        jsr mmu_init
        jsr mmu_bank0

        ; ------------------------------------------- private zero page
        lda #ZP_SENTINEL
        sta zp_probe               ; logical ZP -> physical $1Axx
        jsr mmu_system
        lda zp_probe               ; system ZP again
        cmp sys_zp_before
        bne @zp_done
        lda __COMPILER_ZP_PAGE__ * 256 + zp_probe
        cmp #ZP_SENTINEL
        bne @zp_done
        lda #<CHECK_ZP
        jsr pass
@zp_done:
        jsr mmu_bank0

        ; ---------------------------------- KERNAL calls from both states
        ldy #$00
@say0:  lda bank0_msg,y
        beq @said0
        sty print_y
        jsr kcall_inline
        .word CHROUT
        ldy print_y
        iny
        bne @say0
@said0: jsr common_say_bank1       ; same from the bank-1 state
        lda zp_probe
        cmp #ZP_SENTINEL
        bne @kc_done
        jsr state_is_bank0
        bne @kc_done
        lda kc1_ok
        cmp #$01
        bne @kc_done
        lda #<CHECK_KCALL
        jsr pass
@kc_done:

        ; ------------------------------------------- bank-1 table window
        lda tables_first           ; bank-0 bytes at the same addresses
        sta b0_first
        lda tables_last
        sta b0_last
        lda #<tables_first
        sta mmu_ptr
        lda #>tables_first
        sta mmu_ptr+1
        ldy #$00
        lda #$5A
        jsr mmu_poke1
        lda #<tables_last
        sta mmu_ptr
        lda #>tables_last
        sta mmu_ptr+1
        lda #$A5
        jsr mmu_poke1
        jsr mmu_peek1
        cmp #$A5
        bne @b1_done
        lda #<tables_first
        sta mmu_ptr
        lda #>tables_first
        sta mmu_ptr+1
        jsr mmu_peek1
        cmp #$5A
        bne @b1_done
        lda tables_first
        cmp b0_first
        bne @b1_done
        lda tables_last
        cmp b0_last
        bne @b1_done
        jsr state_is_bank0
        bne @b1_done
        lda #<CHECK_BANK1
        jsr pass
@b1_done:

        ; ----------------------------------------- shared common regions
        lda #$3C
        sta diskbuf
        lda #$C3
        sta scratch
        jsr common_shared_test
        lda shared_ok
        cmp #$01
        bne @sh_done
        lda MB_DATA+7              ; written from the bank-1 state
        cmp #$7E
        bne @sh_done
        lda #<CHECK_COMMON
        jsr pass
@sh_done:
        lda #$00
        sta MB_DATA+7

        ; -------------------------------------- NMI under bank 1 + ZP
        jsr common_nmi_test
        lda MB_DATA+0
        beq @nmi_done              ; the NMI never arrived
        lda MB_DATA+1
        cmp #CR_RAM1_KERNAL
        bne @nmi_done
        lda MB_DATA+2
        cmp #<__COMPILER_ZP_PAGE__
        bne @nmi_done
        lda MB_DATA+3
        cmp #ZP_SENTINEL
        bne @nmi_done
        lda nmi_sp
        cmp entry_sp_inner
        bne @nmi_done
        lda #<CHECK_NMI
        jsr pass
@nmi_done:

        ; ------------------------------------------------- full restore
        jsr mmu_shutdown
        tsx
        cpx entry_sp
        bne @rs_done
        lda MMU_CR
        cmp entry_state+0
        bne @rs_done
        ldx #4
@rs:    lda MMU_RCR,x
        cmp entry_state+1,x
        bne @rs_done
        dex
        bpl @rs
        lda NMINV
        cmp entry_state+6
        bne @rs_done
        lda NMINV+1
        cmp entry_state+7
        bne @rs_done
        lda #<CHECK_RESTORE
        jsr pass
@rs_done:

        ; ------------------------------------------------ report
        lda fail_mask
        sta MB_CODE
        lda fail_mask+1
        sta MB_CODE+1
        lda #<skel_done
        sta MB_ADDR
        lda #>skel_done
        sta MB_ADDR+1
        ldy #ok_msg - messages
        lda fail_mask
        ora fail_mask+1
        bne @fail
        lda #MB_ST_PASS
        bne @report
@fail:  ldy #fail_msg - messages
        lda #MB_ST_FAIL
@report:
        sta MB_STATUS
skel_done:
        plp
@print: lda messages,y
        beq @end
        sty print_y
        jsr CHROUT
        ldy print_y
        iny
        bne @print
@end:   rts

.segment "CODE"

; Clear a passed check (A = low-byte mask; all checks fit in the low byte).
pass:
        eor #$FF
        and fail_mask
        sta fail_mask
        rts

; Z=1 when the MMU shows the exact bank-0 compiler state.
state_is_bank0:
        lda MMU_CR
        cmp #CR_RAM0_KERNAL
        bne @no
        lda MMU_P0L
        cmp #<__COMPILER_ZP_PAGE__
@no:    rts

.ifdef OVERFLOW_MAIN
        .res $9BF3
.endif

.segment "RODATA"
bank0_msg:
        .byte "KCALL FROM BANK 0", $0D, $00
messages:
ok_msg:
        .byte "NOVA128 MAP SKELETON OK", $0D, $00
fail_msg:
        .byte "NOVA128 MAP SKELETON FAIL", $0D, $00

.segment "BSS"
entry_sp:       .res 1
entry_state:    .res 8             ; CR, RCR, P0L, P0H, P1L, P1H, NMINV
sys_zp_before:  .res 1
fail_mask:      .res 2
b0_first:       .res 1
b0_last:        .res 1
print_y:        .res 1

; ---------------------------------------------------------------- COMMON
; These routines run with bank 1 mapped, so they must be in common RAM.
.segment "COMMON"

common_say_bank1:
        lda #$00
        sta kc1_ok
        jsr mmu_bank1
        ldy #$00
@say:   lda bank1_msg,y
        beq @said
        sty say_y
        jsr kcall_inline
        .word CHROUT
        ldy say_y
        iny
        bne @say
@said:  lda MMU_CR                 ; still bank 1 after the KERNAL calls?
        cmp #CR_RAM1_KERNAL
        bne @out
        lda MMU_P0L
        cmp #<__COMPILER_ZP_PAGE__
        bne @out
        inc kc1_ok
@out:   jmp mmu_bank0

common_shared_test:
        lda #$00
        sta shared_ok
        jsr mmu_bank1
        lda diskbuf
        cmp #$3C
        bne @out
        lda scratch
        cmp #$C3
        bne @out
        lda #$7E
        sta MB_DATA+7
        inc shared_ok
@out:   jmp mmu_bank0

common_nmi_test:
        tsx
        stx entry_sp_inner
        jsr mmu_bank1
        lda #$7F                   ; disable all CIA #2 sources, clear flags
        sta CIA2_ICR
        bit CIA2_ICR
        lda #$40
        sta CIA2_TALO
        lda #$00
        sta CIA2_TAHI
        lda mmu_nmi_count
        sta nmi_before
        lda #CIA_ICR_SET | CIA_ICR_TA
        sta CIA2_ICR
        lda #CIA_CRA_START | CIA_CRA_ONESHOT | CIA_CRA_LOAD
        sta CIA2_CRA
        ldx #$00                   ; wait up to ~65K iterations
        ldy #$00
@wait:  lda mmu_nmi_count
        cmp nmi_before
        bne @hit
        dex
        bne @wait
        dey
        bne @wait
@hit:   lda MMU_CR                 ; state right after the NMI returned
        sta MB_DATA+1
        lda MMU_P0L
        sta MB_DATA+2
        lda zp_probe
        sta MB_DATA+3
        tsx                        ; same depth as at routine entry?
        stx nmi_sp
        lda #$7F
        sta CIA2_ICR
        lda #$00
        sta CIA2_CRA
        bit CIA2_ICR
        lda mmu_nmi_count
        sec
        sbc nmi_before
        sta MB_DATA+0
        jmp mmu_bank0

bank1_msg:      .byte "KCALL FROM BANK 1", $0D, $00
kc1_ok:         .byte $00
say_y:          .byte $00
shared_ok:      .byte $00
nmi_before:     .byte $00
nmi_sp:         .byte $00
entry_sp_inner: .byte $00

.ifdef OVERFLOW_COMMON
        .res $0600
.endif