From dc0304a87b299d35c90419afad494c5d0b67a61c Mon Sep 17 00:00:00 2001 From: Sebastien Bourdeauducq Date: Tue, 30 Apr 2013 18:53:40 +0200 Subject: [PATCH] bank/description/CSRStorage: support alignment bits --- migen/bank/description.py | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/migen/bank/description.py b/migen/bank/description.py index 1eb5c2c1..7cc2caa1 100644 --- a/migen/bank/description.py +++ b/migen/bank/description.py @@ -47,14 +47,17 @@ class CSRStatus(_CompoundCSR): self.simple_csrs.append(sc) class CSRStorage(_CompoundCSR): - def __init__(self, size=1, reset=0, atomic_write=False, write_from_dev=False, name=None): + def __init__(self, size=1, reset=0, atomic_write=False, write_from_dev=False, alignment_bits=0, name=None): _CompoundCSR.__init__(self, size, name) - self.storage = Signal(self.size, reset=reset) + self.alignment_bits = alignment_bits + self.storage_full = Signal(self.size, reset=reset) + self.storage = Signal(self.size - self.alignment_bits) + self.comb += self.storage.eq(self.storage_full[self.alignment_bits:]) self.atomic_write = atomic_write if write_from_dev: self.we = Signal() - self.dat_w = Signal(self.size) - self.sync += If(self.we, self.storage.eq(self.dat_w)) + self.dat_w = Signal(self.size - self.alignment_bits) + self.sync += If(self.we, self.storage_full.eq(self.dat_w << self.alignment_bits)) def do_finalize(self, busword): nwords = (self.size + busword - 1)//busword @@ -63,20 +66,25 @@ class CSRStorage(_CompoundCSR): for i in reversed(range(nwords)): nbits = min(self.size - i*busword, busword) sc = CSR(nbits, self.name + str(i) if nwords else self.name) + self.simple_csrs.append(sc) lo = i*busword hi = lo+nbits # read - self.comb += sc.w.eq(self.storage[lo:hi]) + if lo >= self.alignment_bits: + self.comb += sc.w.eq(self.storage_full[lo:hi]) + elif hi > self.alignment_bits: + self.comb += sc.w.eq(Cat(Replicate(0, hi - self.alignment_bits), + self.storage_full[self.alignment_bits:hi])) + else: + self.comb += sc.w.eq(0) # write if nwords > 1 and self.atomic_write: if i: self.sync += If(sc.re, backstore[lo-busword:hi-busword].eq(sc.r)) else: - self.sync += If(sc.re, self.storage.eq(Cat(sc.r, backstore))) + self.sync += If(sc.re, self.storage_full.eq(Cat(sc.r, backstore))) else: - self.sync += If(sc.re, self.storage[lo:hi].eq(sc.r)) - - self.simple_csrs.append(sc) + self.sync += If(sc.re, self.storage_full[lo:hi].eq(sc.r)) def csrprefix(prefix, csrs): for csr in csrs: -- 2.30.2