Add simple button/LED assembler example

Reads out the buttons, displays them on the LEDs. Both are memory mapped.
a3f · Jul 25, 2017 · f7f8bac · f7f8bac
1 parent 91aa468
commit f7f8bac
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diff --git a/vhdl/arch/InstructionMem.vhdl b/vhdl/arch/InstructionMem.vhdl
@@ -38,6 +38,13 @@ architecture behav of InstructionMem is
        X"240200e0", -- li      v0,224
        X"a382012b", -- sb      v0,299(gp)
        X"00000000", -- nop
+
+       X"3c011400", -- lui     at,0x1400
+       X"3c1a1400", -- lui     k0,0x1400
+       X"375a0002", -- ori     k0,k0,0x2
+       X"83420000", -- lb      v0,0(k0)
+       X"a0220000", -- sb      v0,0(at)
+
        X"08000000", -- j       0 <_start>
        X"00000000" -- nop
     );

diff --git a/vhdl/roms/button2leds.S b/vhdl/roms/button2leds.S
@@ -0,0 +1,12 @@
+.set mips1
+.set noreorder
+.set noat
+
+.org 0
+
+li $at, 0x14000000 # LEDs
+li $k0, 0x14000002 # Push buttons
+
+lb $v0, 0($k0)
+sb $v0, 0($at)
+