Add readme; SRA bugfix

Readme.md

@@ -0,0 +1,22 @@
+# Rustyboy
+
+Awesome GB(C?) emulator.
+
+## Current status
+
+Basic instructions are completely implemented, however some prefix instructions are missing.
+Display is able to render tiles + sprites, 8x16 sprites are implemented but untested.
+
+## Test suite
+
+ - Test 01 fails because of DAA
+ - Test 02 fails because interrupts are not fully implemented.
+ - Test 03 fails
+ - Test 04 fails
+ - Test 05 fails
+ - Test 06 passes (LD R, R)
+ - Test 07 fails
+ - Test 08 fails
+ - Test 09 fails
+ - Test 10 passes
+ - Test 11 fails

src/cpu.rs

@@ -191,7 +191,7 @@ impl CPU {
                 self.set_8bit_reg(reg_id, v << 1);
             },
             0x28 ... 0x2F => {
-                let reg_id = (instruction - 0x20) as usize;
+                let reg_id = (instruction - 0x28) as usize;
                 if self.debug {
                     println!("SRA {}", REG_NAMES[reg_id]);
                 }