Merge #57

57: Add mcounteren.rs, cycle[h].rs, instret[h].rs, and update mod.rs r=Disasm a=dkhayes117

I'm not sure the set_clear_csr!() macros are correct in mcounteren.rs.  I get a build error that says `cannot find function `_clear` in this scope`

Co-authored-by: dkhayes117 <dkhayes117@yahoo.com>

Author: bors[bot]

src/register/cycle.rs

@@ -0,0 +1,7 @@
+//! cycle register
+//! Shadow of mcycle register
+//! must have `scounteren::cy` or `mcounteren::cy` bit enabled depending on whether
+//! S-mode is implemented or not
+
+read_csr_as_usize!(0xC00, __read_cycle);
+read_composite_csr!(super::cycleh::read(), read());

src/register/cycleh.rs

@@ -0,0 +1,6 @@
+//! cycleh register
+//! Shadow of mcycleh register (rv32)
+//! must have `scounteren::cy` or `mcounteren::cy` bit enabled depending on whether
+//! S-mode is implemented or not
+
+read_csr_as_usize_rv32!(0xC80, __read_cycleh);