ack/plat/cpm/boot.s
2019-06-11 20:02:03 +02:00

202 lines
3.8 KiB
ArmAsm

#
! $Source$
! $State$
! $Revision$
! Declare segments (the order is important).
.sect .text
.sect .rom
.sect .data
.sect .bss
MAX_ARGV = 8
.sect .bss
STACKSIZE = 2*1024
.comm stack, STACKSIZE
.sect .text
begtext:
! Check if bss would overlap BDOS. We must not overwrite
! BDOS and crash CP/M. We cheat by comparing only high bytes
! of each address.
lxi b, __end
lda 0x0007
mov c, a ! c = high byte of BDOS address
mov a, b ! a = high byte of _end
cmp c
rnc ! emergency exit if a >= c
! We have to clear the bss. (argify requires it.)
lxi h, begbss
lxi b, endbss
mvi e, 0
1:
mov m, e
inx h
mov a, b
cmp h
jnz 1b
mov a, c
cmp l
jnz 1b
! Set up the stack (now it's been cleared, since it's in the BSS).
lxi h, 0
dad sp
shld saved_sp ! save old stack pointer
lxi sp, stack + STACKSIZE
! Initialise the rsts (if desired).
#ifdef USE_I80_RSTS
call .rst_init
#endif
! Now the 'heap'.
lxi h, __end
shld _cpm_ram
! C-ify the command line at 0x0080.
lxi h, 0x0080
mov a, m ! a = length of command line
cpi 0x7F ! 127-byte command lines...
jnz 1f
dcr a ! ...lose the last character
1:
adi 0x81 ! write a 0 at 0x0081+length
mov l, a
mov m, h
! Now argify it.
lxi b, 0x0081 ! bc = command line pointer
lxi h, argv ! hl = argv pointer
loop_of_argify:
ldax b ! a = next character
ora a ! check for end of string
jz end_of_argify
cpi ' ' ! scan for non-space
jz 2f
mov m, c ! put next argument in argv
inx h
mov m, b
inx h
lda argc ! increment argc
inr a
sta argc
cpi MAX_ARGV ! exit loop if argv is full
jz end_of_argify
1: inx b ! scan for space
ldax b
ora a
jz end_of_argify
cpi ' '
jnz 1b
xra a ! replace the space with a '\0'
stax b
2: inx b
jmp loop_of_argify
end_of_argify:
! Add the fake parameter for the program name.
lxi h, progname
shld argv0
lxi h, argc
inr m
! Push the main() arguments and go.
lxi h, envp
push h
lxi h, argv0
push h
lhld argc ! slightly evil
mvi h, 0
push h
push h ! return address is 0
jmp __m_a_i_n
.define _cpm_fastexit
_cpm_fastexit:
saved_sp = _cpm_fastexit + 1
lxi sp, 0 ! patched on startup
ret
! Emergency exit routine.
.define EXIT, __exit, _cpm_exit
EXIT = 0
__exit = 0
_cpm_exit = 0
! Special CP/M stuff.
.define _cpm_fcb
_cpm_fcb = 0x005c
.define _cpm_ram
.comm _cpm_ram, 2
.define _cpm_ramtop
_cpm_ramtop = 0x0001
.define _cpm_default_dma
_cpm_default_dma = 0x0080
.define _cpm_cmdlinelen, _cpm_cmdline
_cpm_cmdlinelen = 0x0080
_cpm_cmdline = 0x0081
! Define symbols at the beginning of our various segments, so that we can find
! them. (Except .text, which has already been done.)
.define begtext, begdata, begbss
.sect .data; begdata:
.sect .rom; begrom:
.sect .bss; begbss:
! Some magic data. All EM systems need these.
.define .ignmask, _errno
.comm .ignmask, 2
.comm _errno, 2
! Used to store the argv array.
argc: .space 1 ! number of args
argv0: .space 2 ! always points at progname
argv: .space 2*MAX_ARGV ! argv array (must be after argv0)
envp: .space 2 ! envp array (always empty, must be after argv)
! These are used specifically by the i80 code generator.
.define .retadr, .retadr1
.define .bcreg, .areg
.define .tmp1, .fra, block1, block2, block3
.comm .retadr, 2 ! used to save return address
.comm .retadr1, 2 ! reserve
.comm .bcreg, 2
.comm .areg, 1
.comm .tmp1, 2
.comm .fra, 8 ! 8 bytes function return area
block1: .space 4 ! used by 32 bits divide and
block2: .space 4 ! multiply routines
block3: .space 4 ! must be contiguous (.comm doesn't guarantee this)
.sect .rom
progname: .asciz 'ACKCPM'