Minimal NXP/Teensy support

src/runtime/volatile/register_nxpmk66f18.go

@@ -0,0 +1,84 @@
+// +build nxp,mk66f18
+
+package volatile
+
+import "unsafe"
+
+const registerBase = 0x40000000
+const registerEnd = 0x40100000
+const bitbandBase = 0x42000000
+const ptrBytes = unsafe.Sizeof(uintptr(0))
+
+//go:inline
+func bitbandAddress(reg uintptr, bit uintptr) uintptr {
+	if bit > ptrBytes*8 {
+		panic("invalid bit position")
+	}
+	if reg < registerBase || reg >= registerEnd {
+		panic("register is out of range")
+	}
+	return (reg-registerBase)*ptrBytes*8 + bit*ptrBytes + bitbandBase
+}
+
+// Special types that causes loads/stores to be volatile (necessary for
+// memory-mapped registers).
+type BitRegister struct {
+	Reg uint32
+}
+
+// Get returns the of the mapped register bit. It is the volatile equivalent of:
+//
+//     *r.Reg
+//
+//go:inline
+func (r *BitRegister) Get() bool {
+	return LoadUint32(&r.Reg) != 0
+}
+
+// Set sets the mapped register bit. It is the volatile equivalent of:
+//
+//     *r.Reg = 1
+//
+//go:inline
+func (r *BitRegister) Set() {
+	StoreUint32(&r.Reg, 1)
+}
+
+// Clear clears the mapped register bit. It is the volatile equivalent of:
+//
+//     *r.Reg = 0
+//
+//go:inline
+func (r *BitRegister) Clear() {
+	StoreUint32(&r.Reg, 0)
+}
+
+// Bit maps bit N of register R to the corresponding bitband address. Bit panics
+// if R is not an AIPS or GPIO register or if N is out of range (greater than
+// the number of bits in a register minus one).
+//
+// go:inline
+func (r *Register8) Bit(bit uintptr) *BitRegister {
+	ptr := bitbandAddress(uintptr(unsafe.Pointer(&r.Reg)), bit)
+	return (*BitRegister)(unsafe.Pointer(ptr))
+}
+
+// Bit maps bit N of register R to the corresponding bitband address. Bit panics
+// if R is not an AIPS or GPIO register or if N is out of range (greater than
+// the number of bits in a register minus one).
+//
+// go:inline
+func (r *Register16) Bit(bit uintptr) *BitRegister {
+	ptr := bitbandAddress(uintptr(unsafe.Pointer(&r.Reg)), bit)
+	return (*BitRegister)(unsafe.Pointer(ptr))
+}
+
+// Bit maps bit N of register R to the corresponding bitband address. Bit panics
+// if R is not an AIPS or GPIO register or if N is out of range (greater than
+// the number of bits in a register minus one).
+//
+// go:inline
+func (r *Register32) Bit(bit uintptr) *BitRegister {
+	ptr := bitbandAddress(uintptr(unsafe.Pointer(&r.Reg)), bit)
+	return (*BitRegister)(unsafe.Pointer(ptr))
+}