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;**************************************************************************
; arch/z80/src/ez80/ez80_startup.asm
;
; Copyright (C) 2008 Gregory Nutt. All rights reserved.
; Author: Gregory Nutt <spudmonkey@racsa.co.cr>
;
; Redistribution and use in source and binary forms, with or without
; modification, are permitted provided that the following conditions
; are met:
;
; 1. Redistributions of source code must retain the above copyright
; notice, this list of conditions and the following disclaimer.
; 2. Redistributions in binary form must reproduce the above copyright
; notice, this list of conditions and the following disclaimer in
; the documentation and/or other materials provided with the
; distribution.
; 3. Neither the name NuttX nor the names of its contributors may be
; used to endorse or promote products derived from this software
; without specific prior written permission.
;
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
; FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
; COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
; BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
; OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
; AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
; ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
; POSSIBILITY OF SUCH DAMAGE.
;
;**************************************************************************
;**************************************************************************
; Included Files
;**************************************************************************
;**************************************************************************
; Constants
;**************************************************************************
;**************************************************************************
; Global symbols used
;**************************************************************************
xref __stack
xref _ez80_init
xref _ez80_initvectors
xref _ez80_initsysclk
xref _ez80_lowinit
xref __low_bss ; Low address of bss segment
xref __len_bss ; Length of bss segment
xref __low_data ; Address of initialized data section
xref __low_romdata ; Addr of initialized data section in ROM
xref __len_data ; Length of initialized data section
xref __copy_code_to_ram
xref __len_code
xref __low_code
xref __low_romcode
xref _os_start
xdef _ez80_startup
xdef _ez80_halt
;**************************************************************************
; Code
;**************************************************************************
segment CODE
.assume ADL=1
;**************************************************************************
; System reset start logic
;**************************************************************************
_ez80_startup:
; Set up the stack pointer at the location determined the lincmd
; file
ld sp, __stack
; Peform chip-specific initialization
call _ez80_init
; initialize the interrupt vector table
call _ez80_initvectors
; Initialize the system clock
call _ez80_initsysclk
; Perform C initializations
; Clear the uninitialized data section
ld bc, __len_bss ; Check for non-zero length
ld a, __len_bss >> 16
or a, c
or a, b
jr z, _ez80_bssdone ; BSS is zero-length ...
xor a, a
ld (__low_bss), a
sbc hl, hl ; hl = 0
dec bc ; 1st byte's taken care of
sbc hl, bc
jr z, _ez80_bssdone ; Just 1 byte ...
ld hl, __low_bss ; reset hl
ld de, __low_bss + 1 ; [de] = bss + 1
ldir
_ez80_bssdone:
; Copy the initialized data section
ld bc, __len_data ; [bc] = data length
ld a, __len_data >> 16 ; Check for non-zero length
or a, c
or a, b
jr z, _ez80_datadone ; __len_data is zero-length ...
ld hl, __low_romdata ; [hl] = data_copy
ld de, __low_data ; [de] = data
ldir ; Copy the data section
_ez80_datadone:
; Copy CODE (which may be in FLASH) to RAM if the
; copy_code_to_ram symbol is set in the link control file
ld a, __copy_code_to_ram
or a, a
jr z, _ez80_codedone
ld bc, __len_code ; [bc] = code length
ld a, __len_code >> 16 ; Check for non-zero length
or a, c
or a, b
jr z, _ez80_codedone ; __len_code is zero-length
ld hl, __low_romcode ; [hl] = code_copy
ld de, __low_code ; [de] = code
ldir ; Copy the code section
_ez80_codedone:
; Perform board-specific intialization
call _ez80_lowinit
; Then start NuttX
call _os_start ; jump to the OS entry point
; NuttX will never return, but just in case...
_ez80_halt:
halt ; We should never get here
jp _ez80_halt
|
