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Line up with 68040 startup

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This commit is contained in:
Vincent Barrilliot 2022-06-04 13:34:48 +02:00
parent 1131efcfb8
commit f0f9a4b62e
1 changed files with 27 additions and 23 deletions
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50
src/m68k/startup_m68k.s
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@ -119,28 +119,22 @@ PENDING_GRP2 = $00B00104
code
coldboot: lea ___STACK,sp
coldboot: move.w #$2700,SR ; Supervisor mode, disable all interrupts
lea ___STACK,sp
bsr _int_disable_all
; Clear BSS segment
lea ___BSSSTART,a0
lea ___BSSSTART,a0
move.l #___BSSSIZE,d0
beq.s callmain
move.l #0,d1
beq callmain
moveq.l #0,d1
clrloop: ; We don't use clr.l because it's a read-modify-write operation
; that is not yet supported by the FPGA's bus logic for now.
; So we use a move instead.
; clr.l (a0)+
move.l d1,(a0)+
subq.l #4,d0
bne.s clrloop
; Set TRAP #15 vector handler
lea h_trap_15,a0 ; Address of the handler
move.l #(13+32)<<2,a1 ; TRAP#15 vector address
move.l a0,(a1) ; Set the vector
bpl.s clrloop
callmain: jsr ___main ; call __main to transfer to the C code
@ -375,6 +369,9 @@ _syscall:
; TRAP#15 handler... transfer control to the C dispatcher
;
h_trap_15:
cmpi.w #$43,d1 ; Is this a sys_proc_elevate call?
beq.s h_trap_elev ; Yes, just handle it here
move.l d6,-(sp) ; Push the parameters to the stack for the C call
move.l d5,-(sp)
move.l d4,-(sp)
@ -387,9 +384,11 @@ h_trap_15:
; Note: the C routine depends upon the register push order
add.l #28,sp ; Remove parameters from the stack
rte ; Return to the caller
h_trap_elev ori #$2000,(a7) ; Change the caller's privilege to supervisor
rte ; And return to it
;
; Jump into a user mode code
;
@ -398,16 +397,21 @@ h_trap_15:
; a1 = location to set user stack pointer
;
_call_user:
move.l (4,a7),a0 ; Get the pointer to the code to start
move.l (8,a7),a1 ; Get the pointer to the process's stack
move.l (12,a7),d0 ; Get the number of parameters passed
move.l (16,a7),a2 ; Get the pointer to the parameters
; andi #$dfff,sr ; Drop into user mode
movea.l a1,a7 ; Set the stack
; Set up the user stack
move.l #$00010000,a0 ; Get the pointer to the process's stack
move.l (12,a7),d1 ; Get the number of parameters passed
move.l (16,a7),a1 ; Get the pointer to the parameters
move.l a1,-(a0) ; Push the parameters list
move.w d1,-(a0) ; Push the parameter count
move.l a0,usp ; Set the User Stack Pointer
move.l a2,-(a7) ; Push the parameters list
move.l d0,-(a7) ; Push the parameter count
jsr (a0)
; Set up the system stack
move.l (4,a7),a0 ; Get the pointer to the code to start
move.w #0,-(a7) ; Push the fake vector offset
move.l a0,-(a7) ; Push it as the starting address
move.w #$0000,-(a7) ; Push the user's initial SR (to switch to user mode)
rte ; Start the user process
_restart_cli:
lea ___STACK,sp