From e02128bd4d9d2716b55be5db3dccb18f92f01e9c Mon Sep 17 00:00:00 2001
From: Brian Cully <bjc@kublai.com>
Date: Sun, 4 Aug 2019 15:33:03 -0400
Subject: Initial commit

---
 src/pipe/addr.rs | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 src/pipe/addr.rs

(limited to 'src/pipe/addr.rs')

diff --git a/src/pipe/addr.rs b/src/pipe/addr.rs
new file mode 100644
index 0000000..b3548cf
--- /dev/null
+++ b/src/pipe/addr.rs
@@ -0,0 +1,98 @@
+/// § 32.8.7.2
+/// Address of the Data Buffer.
+///
+/// Offset: 0x00 & 0x10
+/// Reset: 0xxxxxxxxx
+/// Property: NA
+#[derive(Clone, Copy, Debug)]
+#[repr(C, packed)]
+pub struct Addr(u32);
+
+pub struct R {
+    bits: u32,
+}
+
+pub struct W {
+    bits: u32,
+}
+
+impl Addr {
+    pub fn read(&self) -> R {
+        R { bits: self.0 }
+    }
+
+    pub fn write<F>(&mut self, f: F)
+    where
+        F: FnOnce(&mut W) -> &mut W,
+    {
+        let mut w = W { bits: self.0 };
+        f(&mut w);
+        self.0 = w.bits;
+    }
+
+    pub fn modify<F>(&mut self, f: F)
+    where
+        for<'w> F: FnOnce(&R, &'w mut W) -> &'w mut W,
+    {
+        let r = R { bits: self.0 };
+        let mut w = W { bits: self.0 };
+        f(&r, &mut w);
+        self.0 = w.bits;
+    }
+}
+
+impl From<u32> for Addr {
+    fn from(v: u32) -> Self {
+        Self(v)
+    }
+}
+
+impl R {
+    /// Value in raw bits.
+    pub fn bits(&self) -> u32 {
+        self.bits
+    }
+
+    pub fn addr(&self) -> AddrR {
+        AddrR(self.bits)
+    }
+}
+
+/// Data Pointer Address Value
+///
+/// These bits define the data pointer address as an absolute double
+/// word address in RAM. The two least significant bits must be zero
+/// to ensure the descriptor is 32-bit aligned.
+pub struct AddrR(u32);
+impl AddrR {
+    pub fn bits(&self) -> u32 {
+        self.0
+    }
+}
+
+impl W {
+    /// Write raw bits.
+    pub unsafe fn bits(&mut self, v: u32) -> &mut Self {
+        self.bits = v;
+        self
+    }
+
+    pub fn addr(&mut self) -> AddrW {
+        AddrW { w: self }
+    }
+}
+
+pub struct AddrW<'a> {
+    w: &'a mut W,
+}
+impl<'a> AddrW<'a> {
+    pub unsafe fn bits(self, v: u32) -> &'a mut W {
+        // Address must be 32-bit aligned. cf §32.8.7.2 of SAMD21 data
+        // sheet.
+        assert!((v & 0x3) == 0);
+        self.w.bits = v;
+        self.w
+    }
+
+    // TODO: "safe" method take a pointer instead of raw u32
+}
-- 
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