Imagelibrary/mini-riscv-os
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simplify start.s

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ccckmit
2023-05-24 11:42:54 +08:00
parent 873150ceb9
commit 70443b0ab3
1 changed files with 6 additions and 17 deletions
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A1-Input/start.s
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@@ -1,27 +1,16 @@
# 來源 -- https://matrix89.github.io/writes/writes/experiments-in-riscv/
.equ STACK_SIZE, 8192 .equ STACK_SIZE, 8192
.global _start .global _start
_start: _start:
# setup stacks per hart // hart: hardware thread, 差不多就是 core, 設定此 core 的堆疊 csrr a0, mhartid # 讀取核心代號
csrr t0, mhartid # read current hart id // 讀取 core 的 id bnez a0, park # 若不是 0 號核心，跳到 park 停止
slli t0, t0, 10 # shift left the hart id by 1024 // t0 = t0*1024 la sp, stacks + STACK_SIZE # 0 號核心設定堆疊
la sp, stacks + STACK_SIZE # set the initial stack pointer // 將堆疊指標 sp 放到堆疊底端 j os_main # 0 號核心跳到主程式 os_main
# to the end of the stack space
add sp, sp, t0 # move the current hart stack pointer // 設定 hart 的堆疊位置
# to its place in the stack space
# park harts with id != 0 park:
csrr a0, mhartid # read current hart id
bnez a0, park # if we're not on the hart 0 // 如果不是 hart 0 ，就進入無窮迴圈。
# we park the hart
j os_main # hart 0 jump to c // 堆疊設好了，讓 hart 0 進入 C 語言主程式。
park: # 無窮迴圈，停住!
wfi wfi
j park j park
stacks: stacks:
.skip STACK_SIZE * 4 # allocate space for the harts stacks // 分配堆疊空間 .skip STACK_SIZE # 分配堆疊空間