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.file "boot.c"
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/*
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* Copyright (c) 2018, Marcelo Samsoniuk
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* * Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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.option nopic
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.option nopic
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.text
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.text
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.section .boot
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.align 2
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.align 2
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.globl boot
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.globl check4rv32i
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.type boot, @function
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/*
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boot:
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boot:
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lui a5,%hi(threads)
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- read and increent thread counter
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lw a4,%lo(threads)(a5)
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- case not zero, jump to multi thread boot
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addi sp,sp,-16
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- otherwise continue
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sw s0,8(sp)
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*/
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addi a3,a4,1
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sw a3,%lo(threads)(a5)
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_boot:
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lui a5,%hi(io)
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sw ra,12(sp)
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la a0,threads
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sw s1,4(sp)
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lw a1,0(a0)
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andi a4,a4,1
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addi a2,a1,1
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addi a3,a5,%lo(io)
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sw a2,0(a0)
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li a2,-128
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la a3,io
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sw a4,0(sp)
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bne a1,x0,_multi_thread_boot
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sb a2,3(a3)
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lui s0,%hi(utimers)
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/*
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beqz a4,.L6
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normal boot here:
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li a3,999424
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- set stack
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addi a5,a5,%lo(io)
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- set global pointer
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addi a3,a3,575
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- plot boot banner
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.L2:
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- print memory setup
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lw a4,%lo(utimers)(s0)
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- call main
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addi a1,a4,-1
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- repeat forever
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sw a1,%lo(utimers)(s0)
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*/
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bnez a4,.L4
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lhu a4,8(a5)
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_normal_boot:
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addi a4,a4,1
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slli a4,a4,16
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la sp,_stack
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srli a4,a4,16
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la gp,_global
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sh a4,8(a5)
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sw a3,%lo(utimers)(s0)
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.L4:
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sb a2,3(a5)
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j .L2
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.L6:
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lui s1,%hi(boot)
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.L3:
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call banner
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call banner
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lui a0,%hi(.LC0)
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addi a3,sp,16
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la a3,_stack
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addi a2,s0,%lo(utimers)
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la a2,_heap
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addi a1,s1,%lo(boot)
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sub a4,a3,a2
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addi a0,a0,%lo(.LC0)
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la a1,_boot
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la a0,_boot0msg
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call printf
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call printf
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call main
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call main
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j .L3
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.size boot, .-boot
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j _normal_boot
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.section .rodata.str1.4,"aMS",@progbits,1
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/*
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multi-thread boot:
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- set io base
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- write thread number to io.gpio
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- increent thread number
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- repeat forever
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*/
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_multi_thread_boot:
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sh a1,10(a3)
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addi a1,a1,1
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j _multi_thread_boot
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/*
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rv32e/rv32i detection:
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- set x15 0
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- set x31 1
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- sub x31-x15 and return the value
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why this works?!
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- the rv32i have separate x15 and x31, but the rv32e will make x15 = x31
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- this "feature" probably works only in the darkriscv! :)
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*/
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check4rv32i:
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.word 0x00000793 /* addi x15,x0,0 */
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.word 0x00100f93 /* addi x31,x0,1 */
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.word 0x40ff8533 /* sub a0,x31,x15 */
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ret
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/*
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data segment here!
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*/
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.section .rodata
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.align 2
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.align 2
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.LC0:
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.string "boot0: text@%d data@%d stack@%d\n"
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_boot0msg:
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.ident "GCC: (GNU) 9.0.0 20180818 (experimental)"
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.string "boot0: text@%d data@%d stack@%d (%d bytes free)\n"
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No newline at end of file
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No newline at end of file
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