/* Copyright (c) 2013-2014 Andes Technology Corporation. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 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. The name of the company may not 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 RED HAT INCORPORATED 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. */ ##============================================================================== ## ## crt0.S ## ## nds32 startup code ## ##============================================================================== #include "syscall_extra.h" ##------------------------------------------------------------------------------ ## Vector table setup ##------------------------------------------------------------------------------ .section .nds32_init, "ax" j _start ##------------------------------------------------------------------------------ ## Startup code implementation ##------------------------------------------------------------------------------ .section .text .weak _SDA_BASE_ .weak _ITB_BASE_ .weak _arg_init .weak __pre_c_init .weak __post_c_init .weak _call_exit .global _start .type _start, @function .align 2 _start: /* The initialization sequence really does matter !!! The global pointer must be initialized precedence over all others. */ .L_init_gp: /* Initialization for global pointer. The symbol _SDA_BASE_ is determined by Linker. SDA stands for Small Data Access. */ la $gp, _SDA_BASE_ #if __NDS32_EXT_EX9__ .L_init_itb: /* Initialization for Instruction Table Base (ITB). The symbol _ITB_BASE_ is determined by Linker. Set $ITB only if MSC_CFG.EIT (cr4.b'24) is set. */ mfsr $r0, $MSC_CFG srli $r0, $r0, 24 andi $r0, $r0, 0x1 beqz $r0, 1f /* Fall through ? */ la $r0, _ITB_BASE_ mtusr $r0, $ITB 1: #endif .L_init_sp: /* Initialization for stack pointer. The symbol _stack is defined in linker script. Make sure $sp is 8-byte aligned. */ la $sp, _stack #if __NDS32_ISA_V3__ bitci $sp, $sp, #7 #else movi $r0, #-8 /* Set $r0 as 0xFFFFFFF8. */ and $sp, $sp, $r0 #endif #if __NDS32_EXT_FPU_SP__ || __NDS32_EXT_FPU_DP__ .L_init_fpu: /* Initialize FPU Set FUCOP_CTL.CP0EN (fucpr.b'0). */ mfsr $r0, $FUCOP_CTL ori $r0, $r0, 0x1 mtsr $r0, $FUCOP_CTL dsb /* According to [bugzilla #9425], set flush-to-zero mode. That is, set $FPCSR.DNZ(b'12) = 1. */ FMFCSR $r0 ori $r0, $r0, 0x1000 FMTCSR $r0 dsb #endif .L_pre_c_init: ! call __pre_c_init if provided ! sample __pre_c_init is in BSP la $r15, __pre_c_init ! load address of __pre_c_init beqz $r15, .L_zero_out_bss ! check existence of __pre_c_init jral $r15 ! pre-c-runtime initialization .L_zero_out_bss: /* Zero out the bss section. Equivalence C code for follow part: if (_end == _edata) goto .L_post_c_init unsinged int *ptr = _edata; while (ptr != _end) *ptr++ = 0 $r0 = ptr/_edata $r1 = _end $r2 = 0 */ la $r0, _edata la $r1, _end movi $r2, #0 beq $r0, $r1, .L_post_c_init /* Branch if no bss. */ .Lword_clear: swi.bi $r2, [$r0], #4 bne $r0, $r1, .Lword_clear .L_post_c_init: ! call __post_c_init if provided ! no sample __post_c_init is provided la $r15, __post_c_init ! load address of __post_c_init beqz $r15, .L_arg_init ! check existence of __post_c_init jral $r15 ! post-c-runtime initialization .L_arg_init: ! argc/argv initialization if necessary la $r7, _arg_init ! get address of _arg_init beqz $r7, .L_clean_reg ! if there isn't _arg_init, go main addi $sp, $sp, -512 ! allocate space for command line ! and arguments move $r6, $sp ! r6 = buffer addr of cmd line move $r0, $r6 ! r0 = buffer addr of cmd line syscall SYS_getcmdline ! get cmd line move $r0, $r6 ! r0 = buffer addr of cmd line addi $r1, $r6, 256 ! r1 = argv jral $r7 ! init argc/argv addi $r1, $r6, 256 ! r1 = argv b .L_call_main .L_clean_reg: /* Prepare argc/argv/env for main function. Since there is no operating system so far, we set $r0, $r1, and $r2 to be zero. Note: $r2 already set to zero in .L_zero_out_bss: code fragment. */ movi $r0, 0 movi $r1, 0 movi $r2, 0 .L_call_main: /* Call 'main'. */ bal main /* Call _call_exit. */ ! call _call_exit if necessary; default implementation is in crtexit.c la $r15, _call_exit ! load address of _call_exit beqz $r15, .L_terminate_program ! no _call_exit? go exit jral $r15 ! _call_exit will never return .L_terminate_program: /* There are two ways to terminate program: 1. User "syscall 0x1" directly. 2. Call exit. The return value $r0 from main() is implicitly passed as argument. Currently, we use option 2 as a solution to follow C99 5.1.2.2.3, but aware that general exit() will do some cleanup procedures which may result in large-memory-footprints. */ bal exit .L_forever_loop: /* Should never return here. */ b .L_forever_loop .size _start, .-_start