1// Copyright 2015-2020 Espressif Systems (Shanghai) PTE LTD
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15    .section .text
16
17    .global esp_shared_stack_invoke_function
18    .type esp_shared_stack_invoke_function, @function
19esp_shared_stack_invoke_function:
20    /* save current stack and return address */
21    mv t0, sp
22    mv t1, ra
23
24    /* Set shared stack as new stack pointer */
25    mv sp, a1
26
27    /* store the ra and previous stack pointer in a safe place
28       stack pointer for riscv should always be 16 byte aligned */
29    addi sp,sp,-16
30    sw  t0, 0(sp)
31    sw  t1, 4(sp)
32
33    /* call the subroutine */
34    jalr a0, 0
35
36    /* gets the ra and stack pointer saved previously */
37    lw  t0, 0(sp)
38    lw  t1, 4(sp)
39    addi sp, sp, 16
40
41    /* restore both ra and real stack pointer of current task */
42    mv ra, t1
43    mv sp, t0
44    ret
45