sram: fix sub-word write

milkymist/sram/__init__.py

@@ -9,7 +9,7 @@ class SRAM:
 	def get_fragment(self):
 		# generate write enable signal
 		we = Signal(BV(4))
-		comb = [we[i].eq(self.bus.cyc_i & self.bus.stb_i & self.bus.we_i & self.bus.sel_i[3-i])
+		comb = [we[i].eq(self.bus.cyc_i & self.bus.stb_i & self.bus.we_i & self.bus.sel_i[i])
 			for i in range(4)]
 		# split address
 		nbits = bits_for(self.depth-1)

top.py

@@ -8,7 +8,7 @@ import constraints
 def get():
 	MHz = 1000000
 	clk_freq = 80*MHz
-	sram_size = 4096 # in kilobytes
+	sram_size = 4096 # in bytes
 	
 	clkfx_sys = clkfx.ClkFX(50*MHz, clk_freq)
 	reset0 = m1reset.M1Reset()