| <!-- |
| Copyright 2019, Data61, CSIRO (ABN 41 687 119 230) |
| |
| SPDX-License-Identifier: CC-BY-SA-4.0 |
| --> |
| |
| # Calling Conventions for RISC-V 64-bit |
| |
| * `sp` contains the stack pointer, |
| * `fp` (`s0`) contains the frame pointer, |
| * `ra` contains the return address, |
| * `a0` to `a7` are used to pass the first 8 arguments to a subroutine. |
| * `a0` to `a1` are used to subroutine return values. |
| |
| ## Prologue |
| |
| 1. push the value of `ra` onto the stack, |
| 2. push the value of `fp` onto the stack, then |
| 3. read the current value of `sp` into `fp`. |
| |
| ```asm |
| addi sp, sp, -16 |
| sd s0, 0(sp) |
| sd ra, 8(sp) |
| addi s0, sp, 0 |
| ``` |
| |
| ## Epilogue |
| |
| ```asm |
| addi sp, s0, 0 |
| ld ra, 8(sp) |
| ld s0, 0(sp) |
| addi sp, sp, 16 |
| ret |
| ``` |
