57 lines
1.6 KiB
ArmAsm
57 lines
1.6 KiB
ArmAsm
|
##==============================================================================
|
||
|
|
##
|
||
|
|
## crt0.S
|
||
|
|
##
|
||
|
|
## IQ2000 startup code
|
||
|
|
##
|
||
|
|
##==============================================================================
|
||
|
|
##
|
||
|
|
## Copyright (c) 2000, Cygnus Solutions, A Red Hat Company
|
||
|
|
##
|
||
|
|
## The authors hereby grant permission to use, copy, modify, distribute,
|
||
|
|
## and license this software and its documentation for any purpose, provided
|
||
|
|
## that existing copyright notices are retained in all copies and that this
|
||
|
|
## notice is included verbatim in any distributions. No written agreement,
|
||
|
|
## license, or royalty fee is required for any of the authorized uses.
|
||
|
|
## Modifications to this software may be copyrighted by their authors
|
||
|
|
## and need not follow the licensing terms described here, provided that
|
||
|
|
## the new terms are clearly indicated on the first page of each file where
|
||
|
|
## they apply.
|
||
|
|
##
|
||
|
|
|
||
|
|
##------------------------------------------------------------------------------
|
||
|
|
|
||
|
|
.file "crt0.S"
|
||
|
|
|
||
|
|
##------------------------------------------------------------------------------
|
||
|
|
## Startup code
|
||
|
|
.section .text
|
||
|
|
.global _start
|
||
|
|
_start:
|
||
|
|
lui %29,%hi(__stack)
|
||
|
|
ori %29,%29,%lo(__stack)
|
||
|
|
|
||
|
|
lui %24,%hi(_edata) # get start of bss
|
||
|
|
ori %24,%24,%lo(_edata)
|
||
|
|
|
||
|
|
lui %25,%hi(_end) # get end of bss
|
||
|
|
ori %25,%25,%lo(_end)
|
||
|
|
|
||
|
|
beq %24,%25,.L0 # check if end and start are the same
|
||
|
|
# do nothing if no bss
|
||
|
|
|
||
|
|
.L1:
|
||
|
|
sb %0,0(%24) # clear a byte and bump pointer
|
||
|
|
addi %24,%24,1
|
||
|
|
bne %24,%25,.L1
|
||
|
|
nop
|
||
|
|
|
||
|
|
.L0:
|
||
|
|
jal _main # call _main to run ctors/dtors
|
||
|
|
nop
|
||
|
|
xor %4,%4,%4
|
||
|
|
jal main # call main program
|
||
|
|
xor %5,%5,%5
|
||
|
|
jal exit # all done, no need to return or
|
||
|
|
or %4,%0,%2 # exit with main's return value
|