;
-; We have 12K loaded D000-FFFF. We actually keep ourselves highish up
-; to leave lots of room to load code
+; This will need our own SCM module as well because the CP/M loader
+; moves CP/M and trashes SCM before running it.
;
; Currently this and the glue driver code is well under 2 disk blocks.
; Adding partitions should still fit 2 blocks nicely.
.area _CODE
;
-; The main loop. We wait for about 2 seconds looking for input. If we
-; see input then we go to command line mode, if not we load the
-; default image name. If the default fails we then drop into command
-; line mode.
+; Magic for the loader
;
-; Right now we treat anything as a filename, except * which indicates
-; platform specific helpers. We may add other commands later (eg
-; single letters to switch drive).
-;
-boot_begin:
- ; Run anything system specific
- call preboot
- ld hl,#filo
- call con_write
- ; Load the partition table and find our partition
- call partitions
-boot_up:
- ld hl,#prompt
- call con_write
- ld b,#200 ; 2 seconds
-boot_wait:
- push bc
- call con_check
- jr nz, con_prompt
- call delay10ms
- pop bc
- djnz boot_wait
-boot_default:
- ld hl,#newline
- call con_write
- ld hl,#defname
-boot_name:
- ld de,#loadname
- ld bc,#31
- ldir
- call load_kernel
- ld hl,#failed
- call con_write
-con_next:
- ld hl,#prompt
- call con_write
-con_prompt:
- call con_readbuf
- jr z, con_next
- ld a,(hl)
- cp #'*'
- jr nz, boot_name
- call system
- jr con_next
+ .byte 'Z'
+ .byte 80
-prompt:
- .asciz 'FILO: '
-failed:
- .ascii 'Load failed.'
-newline:
- .asciz '\n'
-defname:
- .asciz 'fuzix'
-filo:
- .ascii 'Fuzix Intermediate Loader v0.01.\n'
- .asciz '(C)2019 Alan Cox\n\n'
-
- .area _DATA
-
-loadname:
- .ds 31
-ibuf:
- .ds 64
-dbuf:
- .ds 512
-partbase_l:
- .dw 0
-partbase_h:
- .dw 0
-
- .area _CODE
-
-partitions:
- ; No partitions found (hack for now)
- ld hl,#0
- ld (partbase_l),hl
- ld (partbase_h),hl
- ret
-;
-; We have set the base according to the partition table, work relative
-; to it
-;
-; The key to this being small is that a directory is a special kind of
-; file. We therefore only need one routine which loads a file at the
-; load address to do all the work. We load inode 1 (/) and find the
-; file, then we use the same function to load the actual file.
;
-; We could easily add subdirectories if we wanted.
+; Loader core
;
-; The data loading is kept compact by having a routine to load an
-; array of block numbers. That same logic works for both the direct
-; blocks and the first indirect (which is all we care about).
-;
-load_kernel:
- ;
- ; Load the super block
- ;
- ld de,#1 ; 0 is the boot block space, 1 the superblock
- ld hl,#dbuf
- call bread
- ret nz
- ;
- ; Check the superblock is valid
- ;
- ld hl,(dbuf)
- ld de,#12742 ; file system
- or a
- sbc hl,de
- ret nz ; not valid
- ;
- ; It's a filesystem so we can load inode 1
- ;
- ld hl,#1
- ld a,#DIRTYPE ; want a directory
-
- call loadi ; load / into memory
- ; returns DE = size
- ret nz ; / failed to load or too large
- ld ix,#loadbuf ; start pointer into IX
- ;
- ; Turn the size into a record count of 32 byte records
- ;
- ld b,#5
-shift5:
- srl d
- srl e
- djnz shift5
- ; DE is now record count
-
- ;
- ; Scan the loaded file (directory) for the wanted name entry
- ;
-find_by_name:
- push de
- ld hl,#loadname
- push ix
- call cmpname
- pop ix
- jr nz, next_name
- ld l,30(ix)
- ld h,31(ix)
- ld a,h ; empty slot even if matched
- or l
- jr nz, found_name
-next_name:
- ;
- ; Move on a record
- ;
- ld de,#32
- add ix,de
- pop de
- dec de
- ld a,d
- or e
- jr nz, find_by_name
- ;
- ; Not found
- ;
- inc a ; force NZ
- ret ; not found
- ;
- ; Name match found
- ;
-found_name:
- pop af ; Discard top of stack
- ld a,#FILETYPE ; must be a file
- call loadi ; replace the directory load with the target
- ret nz
- ;
- ; And launch
- ;
- jp loadbuf
-
-;
-; Load a file or directory if not too big
-;
-loadi:
- ; A is the required type, HL the inode
- call iget ; get the relevant inode into the ibuf
- ret nz
- ld de, (ibuf+I_SIZE+2)
- ld a,d
- or e
- ret nz ; over 64K
- ld de, (ibuf+I_SIZE)
- ld a,#0xE0
- cp d
- jr nc, retnz ; too big too load
-
- ld a,e
- or a
- jr z, directs ; exact blocks
- inc d ; load the partial
- ;
- ; Now it's load time
- ;
-directs:
- push de
- ld a,d ; number of blocks
- cp #18
- jr z, shortfile
- ld a,#18 ; direct blocks
-shortfile:
- ld b,a
- ld hl,#loadbuf
- ld ix,#ibuf + I_ADDR
- call breadset ; read b blocks from the list in ix
- pop de
- ret nz
- ; See what indirects are needed if any
- ld a,d
- cp #19
- jr c, load_done
- push de
- push hl
- ld e,(ix)
- inc ix
- ld d,(ix)
- inc ix
- ld hl,#dbuf
- call bread ; load the indirect block
- pop de
- pop hl
- ld a,d
- sub #18 ; direct blocks
- ld b,a ; remainder
- ld ix,#dbuf
- call breadset
- ret nz
-load_done:
- ; File now loaded
- xor a
- ret
-retnz:
- or a
- ret
-
-;
-; Load inode HL into ibuf
-;
-; Entry: HL = inode number, A = type bits
-;
-; Return: NZ = error, Z = ok, data in ibuf
-;
-; Destroys: AF/BC/DE/HL
-;
-iget:
- ; Turn an inode into a block
- push af
- push hl
- ex de,hl
- srl d ; Divide inode by 8 (64 bytes per inode)
- srl e
- srl d
- srl e
- srl d
- srl e
- ld hl,#dbuf
- call bread
- pop hl
- jr nz, badiget
- ld a,l
- and #0x07 ; inode offset in block
- add a,a ; x2
- add a,a ; x4
- add a,a ; x8
- add a,a ; x16
- add a,a ; x32
- ld h,#0
- ld l,a
- add hl,hl ; x64
- ld de,#dbuf
- add hl,de ; valid pointer
- ex de,hl
- ld hl,#I_TYPE+1
- add hl,de ; hl is now the type bits
- ld a,(hl)
- and #0xF0 ; type bits
- ld l,a
- pop af
- cp l
- ret nz ; wrong type of file
- ex de,hl ; get pointer back into hl
- ld de,#ibuf
- ld bc,#64
- ldir
- ret ; Z
-badiget:
- pop af
- ret
-
-;
-; Read a set of blocks listed in the array at ix. Any zero entry means
-; a sparse block (zero the memory).
-;
-; Entry: IX = table, B = count, HL = load address
-;
-; Return: Z = success, HL = next load address
-;
-; Destroys: AF BC DE IX
-;
-;
-breadset:
-reader_loop:
- ld e,(ix)
- inc ix
- ld d,(ix)
- inc ix
- push bc
- call bread ; read block DE to HL and move HL on
- pop bc
- ret nz
- djnz reader_loop
- ret
-
-;
-; bread
-;
-; Load a disk block (512 bytes) or zero block
-;
-; HL = buffer to read into
-; DE = block relative to partbase
-;
-; return
-; NZ = fail, Z = ok
-; HL = next read address
-; BC, DE, AF destroyed
-; IX, IY preserved
-;
-bread:
- ld a,d
- or e
- jr nz, bread_disk
- ld d,h
- ld e,l
- ld bc,#511
- ld (hl),#0
- inc de
- ldir
- inc hl
- ret
-
-;
-; Compare the name at IX with the one in HL
-;
-; Returns Z = matched
-;
-; Destroys BC,HL,IX
-;
-;
-cmpname: ; check name in IX matches HL for 30 chars
- ld b,#30
-cmploop:
- ld a,(ix)
- cp (hl)
- ret nz
- or a
- ret z ; First matched \0 matches all
- inc hl
- inc ix
- djnz cmploop
- ret ; Z
-
-
+ .include '../filo/filo.s'
;
; ****************************************************************************
;
xor a
ret
+;
+; Drive Set
+;
+; A = drive 0-15
+;
+; For now just drive A
+;
+drive_set:
+ or a
+ ret z
+ ld hl,#bad_drive
+ jr con_write
+
+bad_drive:
+ .asciz 'Invalid drive.\n'
+;
;
; Console I/O
;
public / FUZIX.git / commitdiff