Merge #90

90: add asm::nop, asm::delay, and delay.rs. r=Disasm a=dkhayes117

update assembly binaries.
update CHANGELOG.md

Co-authored-by: dkhayes117 <[email protected]>
Co-authored-by: Daniel Hayes <[email protected]>
Co-authored-by: Vadim Kaushan <[email protected]>

Author: 3 people

CHANGELOG.md

@@ -11,6 +11,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Add enums `Range`, `Permission` for PMP configuration
 - Add `set_pmp()` and `clear_pmp()` functions to pmpcfg(x) modules
 - Add struct `Pmpcsr` and is returned from `pmpcfgx::read()`
+- Add delay structure and methods using embedded-hal traits and `mcycle` register
+- Add `asm::delay()` function for assembly-based busy-loops
+- Add `asm::nop()`, a wrapper for implementing a `nop` instruction
 
 ### Changed
 

Cargo.toml

@@ -18,6 +18,7 @@ targets = [
 [dependencies]
 bare-metal = "1.0.0"
 bit_field = "0.10.0"
+embedded-hal = "0.2.6"
 
 [build-dependencies]
 riscv-target = "0.1.2"

asm.S

@@ -1,5 +1,11 @@
 #include "asm.h"
 
+.section .text.__nop
+.global __nop
+__nop:
+    nop
+    ret
+
 .section .text.__ebreak
 .global __ebreak
 __ebreak:
@@ -24,6 +30,14 @@ __sfence_vma:
     sfence.vma a0, a1
     ret
 
+.section .text.__delay
+.global __delay
+__delay:
+    1:
+    addi a0, a0, -1
+    bne a0, zero, 1b
+    ret
+
 // User Trap Setup
 RW(0x000, ustatus)  // User status register
 RW(0x004, uie)      // User interrupt-enable register