From 31b84bc12dba41ee48331bc8a776da2a662b4f33 Mon Sep 17 00:00:00 2001
From: occheung <dc@m-labs.hk>
Date: Thu, 13 Aug 2020 16:31:27 +0800
Subject: [PATCH] cfg_reg: mv bitmask operation to macro

---
 src/config_register.rs | 47 ++++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/src/config_register.rs b/src/config_register.rs
index c2f72da..5e41884 100644
--- a/src/config_register.rs
+++ b/src/config_register.rs
@@ -4,9 +4,11 @@ use crate::Error;
 
 /*
  * Macro builder for bit masks
+ * Assumption: Contiguous bit field
+ * Break the bit field up when invoking macro rule if needed
  */
 macro_rules! construct_bitmask {
-	($collection: ident; $($name: ident, $shift: expr, $width: expr),+) => {
+	($collection: ident; $unsigned_type: ty; $($name: ident, $shift: expr, $width: expr),+) => {
 		#[derive(Debug, Copy, Clone)]
 		pub enum $collection {
 			$(
@@ -29,25 +31,32 @@ macro_rules! construct_bitmask {
 					)*
 				}
 			}
-			pub(crate) fn get_bitmask(self) -> u32 {
-				match self {
-					$(
-						$collection::$name => {
-							let mut mask: u32 = 0;
-							for bit in 0..$width {
-								mask |= (1 << ($shift + bit));
-							}
-							mask
-						},
-					)*
+			pub(crate) fn get_bitmask(self) -> $unsigned_type {
+				let mut mask: $unsigned_type = 0;
+				for bit in 0..self.get_width() {
+					mask |= (1 << (self.get_shift() + bit));
 				}
+				mask
+			}
+			pub(crate) fn get_shifted_bits(self, arg: $unsigned_type) -> $unsigned_type {
+				assert!(arg < (2 << self.get_width()));
+				(arg << self.get_shift())
+			}
+			pub(crate) fn set_data_by_arg(self, data: &mut $unsigned_type, arg: $unsigned_type) {
+				// Clear bits in field, then insert shifted argument
+				*data &= (!self.get_bitmask());
+				*data |= self.get_shifted_bits(arg);
+			}
+			pub(crate) fn get_filtered_content(self, data: $unsigned_type) -> $unsigned_type {
+				// Filter everything
+				((data & self.get_bitmask()) >> self.get_shift())
 			}
 		}
 	}
 }
 
 // Bitmasks for CFG
-construct_bitmask!(CFGMask;
+construct_bitmask!(CFGMask; u32;
 	RF_SW,		0,	4,
 	LED,		4,	4,
 	PROFILE,	8,	3,
@@ -62,7 +71,7 @@ construct_bitmask!(CFGMask;
 );
 
 // BitMasks for CFG read
-construct_bitmask!(StatusMask;
+construct_bitmask!(StatusMask; u32;
 	RF_SW,		0,	4,
 	SMP_ERR,	4,	4,
 	PLL_LOCK,	8,	4,
@@ -111,13 +120,7 @@ where
 	 */	
 	pub fn set_configurations(&mut self, configs: &mut[(CFGMask, u32)]) -> Result<u32, Error<E>> {
 		for config in configs.into_iter() {
-			// Erase the bits in the configuration region
-			self.data &= (!config.0.get_bitmask());
-			// Check validity of config data
-			let shifted_config: u32 = config.1 << config.0.get_shift();
-			assert_eq!(shifted_config | config.0.get_bitmask(), config.0.get_bitmask());
-			// Write the configuration onto local data
-			self.data |= shifted_config;
+			config.0.set_data_by_arg(&mut self.data, config.1)
 		}
 		// Write all configurations at the same time
 		self.set_all_configurations()
@@ -127,7 +130,7 @@ where
 	 * Return selected configuration field
 	 */
 	pub fn get_configuration(&mut self, config_type: CFGMask) -> u8 {
-		((self.data & config_type.get_bitmask()) >> config_type.get_shift()) as u8
+		(config_type.get_filtered_content(self.data) as u8)
 	}
 
 	/*