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|
; =============================================================================
; dmesg.asm - kernel boot spew: everything the kernel knows implicitly before
; init spawns, printed dmesg-style on the LCD console (and mirrored over the
; link port, so a gbhub logs the whole boot).
;
; The info costs nothing to know:
; - the boot ROM hands the console model in A/B at entry (saved to wBootA/B)
; - the cartridge describes itself in its own header ($0147-$0149)
; - the CGB memory map is a constant of the hardware
; - subsystem shapes (proc slots, sockets, program table) are link-time facts
; - fs_init just mounted (or formatted) the disk and left the block bitmap
; in fs_bmbuf - counting free blocks is a 16-byte popcount
; =============================================================================
INCLUDE "include/gbos.inc"
SECTION "dmesg", ROM0
; -----------------------------------------------------------------------------
; kernel console output (boot-time: no process context, so KPutc is unusable)
; -----------------------------------------------------------------------------
; kputc(A = char) - LCD terminal + serial mirror. Preserves BC/DE/HL.
kputc::
push bc
push de
push hl
ld b, a
ld [rSB], a ; mirror to the link (gbhub console log)
ld a, $81
ld [rSC], a
ld a, b
call term_putc
pop hl
pop de
pop bc
ret
; kputs(HL = NUL-terminated string). Clobbers A, HL.
kputs::
.l
ld a, [hl+]
or a
ret z
call kputc
jr .l
; kputhex(A = byte) - two uppercase hex digits. Clobbers A.
kputhex::
push af
swap a
call .nib
pop af
.nib
and $0F
add "0"
cp "9" + 1
jr c, .put
add "A" - "9" - 1
.put
jp kputc
; kputdec(A = 0..255) - decimal, no leading zeros. Clobbers A, BC, DE.
kputdec::
ld c, 0 ; "printed a digit yet" flag
ld b, 100
call .digit
ld b, 10
call .digit
add "0"
jp kputc ; ones digit always prints
.digit ; A/B -> A = remainder; prints quotient digit
ld e, 0
.sub
cp b
jr c, .rem
sub b
inc e
jr .sub
.rem
ld d, a
ld a, e
or c
jr z, .skip ; leading zero
ld a, e
add "0"
call kputc
ld c, 1
.skip
ld a, d
ret
; -----------------------------------------------------------------------------
; boot_banner - kernel line + console model + cart header + memory map + proc
; shape. Called right after term_init.
; -----------------------------------------------------------------------------
boot_banner::
ld hl, .s_kernel
call kputs
; console model: boot ROM leaves A=$11 (CGB/AGB, B bit0 = AGB), $01 (DMG),
; $FF (MGB/pocket)
ld hl, .s_console
call kputs
ld a, [wBootA]
cp $11
jr nz, .not_cgb
ld a, [wBootB]
bit 0, a
jr z, .cgb
ld hl, .s_agb
jr .model
.cgb
ld hl, .s_cgb
jr .model
.not_cgb
cp $01
jr nz, .not_dmg
ld hl, .s_dmg
jr .model
.not_dmg
ld hl, .s_mgb
.model
call kputs
ld hl, .s_boota
call kputs
ld a, [wBootA]
call kputhex
ld a, ")"
call kputc
ld a, 10
call kputc
; cart: the header describes the very cartridge we run from
ld hl, .s_cart
call kputs
ld a, [$0147] ; cart type
cp $19
jr c, .rawtype
cp $1F
jr nc, .rawtype
ld hl, .s_mbc5
call kputs
jr .romsize
.rawtype
ld hl, .s_type
call kputs
ld a, [$0147]
call kputhex
.romsize
ld hl, .s_rom
call kputs
ld a, [$0148] ; ROM size code: 32K << code
cp 9
jr nc, .romq
add a ; *2: word index into the pointer table
ld e, a
ld d, 0
ld hl, .romtab
add hl, de
ld a, [hl+]
ld h, [hl]
ld l, a
jr .romp
.romq
ld hl, .s_unk
.romp
call kputs
ld hl, .s_sram
call kputs
ld a, [$0149] ; cart RAM size code
cp 6
jr nc, .ramq
add a
ld e, a
ld d, 0
ld hl, .ramtab
add hl, de
ld a, [hl+]
ld h, [hl]
ld l, a
jr .ramp
.ramq
ld hl, .s_unk
.ramp
call kputs
ld hl, .s_sram2
call kputs
; memory map: hardware constants of the CGB
ld hl, .s_mem
call kputs
; processes + programs: link-time shape of the kernel
ld hl, .s_proc
call kputs
ld hl, ProgramTableEnd - ProgramTable ; bytes; 4 per entry
ld a, l
srl h
rra
srl h
rra ; /4 (table < 1K, fits in A)
call kputdec
ld hl, .s_progs
call kputs
ret
.s_kernel: db "gbos sm83 microkernel\n", 0
.s_console: db "console: ", 0
.s_cgb: db "CGB", 0
.s_agb: db "AGB", 0
.s_dmg: db "DMG", 0
.s_mgb: db "MGB", 0
.s_boota: db " (boot a=$", 0
.s_cart: db "cart: ", 0
.s_mbc5: db "mbc5", 0
.s_type: db "type $", 0
.s_rom: db ", ", 0
.s_sram: db " rom, ", 0
.s_sram2: db " sram\n", 0
.s_unk: db "?", 0
.s_mem: db "mem: 32K wram 16K vram 127B hram\n", 0
.s_proc: db "proc: {d:MAX_PROCS} slots, ", 0
.s_progs: db " programs\n", 0
.romtab: dw .r0, .r1, .r2, .r3, .r4, .r5, .r6, .r7, .r8
.r0: db "32K",0
.r1: db "64K",0
.r2: db "128K",0
.r3: db "256K",0
.r4: db "512K",0
.r5: db "1M",0
.r6: db "2M",0
.r7: db "4M",0
.r8: db "8M",0
.ramtab: dw .m0, .m1, .m2, .m3, .m4, .m5
.m0: db "no",0
.m1: db "2K",0
.m2: db "8K",0
.m3: db "32K",0
.m4: db "128K",0
.m5: db "64K",0
; -----------------------------------------------------------------------------
; boot_net - after net_init: the link is the network.
; -----------------------------------------------------------------------------
boot_net::
ld hl, .s
call kputs
ret
.s: db "net: slip on link port, {d:MAX_SOCKS} sockets\n", 0
; -----------------------------------------------------------------------------
; boot_fs - after fs_init: mounted vs freshly formatted, and free blocks
; (popcount of clear bits in the block bitmap fs_init left in fs_bmbuf).
; -----------------------------------------------------------------------------
boot_fs::
ld hl, .s_fs
call kputs
ld a, [wBootFsFresh]
or a
jr z, .mounted
ld hl, .s_fresh
call kputs
jr .count
.mounted
ld hl, .s_mount
call kputs
.count
ld hl, fs_bmbuf
ld b, FS_NBLOCKS / 8
ld c, 0 ; free-block count
.byte
ld a, [hl+]
cpl ; set bits = free blocks
ld e, 8
.bit
rra
jr nc, .nofree
inc c
.nofree
dec e
jr nz, .bit
dec b
jr nz, .byte
ld a, c
call kputdec
ld hl, .s_of
call kputs
ld a, FS_NBLOCKS
call kputdec
ld hl, .s_blkfree
call kputs
ret
.s_fs: db "fs: gbfs v{d:FS_VERSION} ", 0
.s_mount: db "mounted, ", 0
.s_fresh: db "formatted, ", 0
.s_of: db "/", 0
.s_blkfree: db " blk free\n", 0
; -----------------------------------------------------------------------------
; boot_tty / boot_init - console shape, and the handoff line.
; -----------------------------------------------------------------------------
boot_tty::
ld hl, .s
call kputs
ret
.s: db "tty: 40x18 console, SELECT = osk\n", 0
boot_init::
ld hl, .s
call kputs
ret
.s: db "init: spawning pid 1\n", 0
|
