Add helper getBits() for decode w/ S

src/decode.c

@@ -0,0 +1,26 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "decode.h"
+
+#define BYTE_BITS 8
+
+// Retrieve the bits between positions 'lsb' (inclusive) and 'msb' (exclusive) from a given word 
+// as a new zero-extended word.
+static word getBits(word wrd, uint8_t lsb, uint8_t msb) {
+
+    // Ensure LSB and MSB are within range of word size, and in the correct order
+    assert(lsb < msb && msb < BYTE_BITS);
+
+    wrd &= (1 << msb) - 1;
+    return wrd >> lsb;
+}
+
+a64inst_instruction *decode(word wrd) {
+
+    a64inst_instruction *inst = malloc(sizeof(a64inst_instruction));
+    if (inst == NULL) {
+        fprintf(stderr, "Ran out of memory while attempting to decode an instruction!\n");
+        exit(1);
+    }
+}

src/decode.h

@@ -0,0 +1,4 @@
+#include "global.h"
+#include "a64instruction.h"
+
+a64inst_instruction *decode(word w);