MNRS-BM-BSP/env/start.S

67 lines
962 B
ArmAsm

#include "encoding.h"
// See LICENSE for license details.
.section .init
.globl _start
.type _start,@function
_start:
.option push
.option norelax
.option norvc
j 1f
.2byte 0x4e4d
.2byte 0x5352
.4byte 0x669
1:
la gp, __global_pointer$
.option pop
la sp, _sp
la t0, trap_entry
csrw mtvec, t0
/* Load data section */
la a0, _data_lma
la a1, _data
la a2, _edata
bgeu a1, a2, 2f
1:
lw t0, (a0)
addi a0, a0, 4
sw t0, (a1)
addi a1, a1, 4
bltu a1, a2, 1b
2:
/* Clear bss section */
la a0, __bss_start
la a1, _end
bgeu a0, a1, 2f
1:
sw zero, (a0)
addi a0, a0, 4
bltu a0, a1, 1b
2:
/* Call global constructors */
#ifndef HAVE_NO_INIT_FINI
la a0, __libc_fini_array
call atexit
call __libc_init_array
#endif
#ifndef __riscv_float_abi_soft
/* Enable FPU */
li t0, MSTATUS_FS
csrs mstatus, t0
csrr t1, mstatus
and t1, t1, t0
beqz t1, 1f
fssr x0
1:
#endif
/* argc = argv = 0 */
li a0, 0
li a1, 0
call main
tail _exit