Implement streq routine

tests/harness.s

@@ -55,3 +55,30 @@ read:
     li a0, 0            # 0 = standard input (stdin)
     ecall               # invoke syscall
     ret
+
+
+# Determine if two strings are equal
+#    arguments:
+#       a0: address of first string
+#       a1: length of first string
+#       a2: address of second string
+#       a3: length of second string
+#    return:
+#       a0: 1 if equal, 0 otherwise
+streq:
+    bne a1, a2, 2f      # If the lengths are not the same then the strings are different
+1:
+    beqz a1, 3f         # If the remaining length is zero, string are the same
+    lbu a4, 0(a0)       # load byte from string 1
+    lbu a5, 0(a2)       # load byte from string 2
+    bne a4, a5, 2f      # return false if bytes are not equal
+    addi a1, a1, -1     # decrement a1
+    addi a0, a0, 1      # go to next byte of string 1
+    addi a2, a2, 1      # go to next byte of string 2
+    j 1b                # loop
+2:
+    li a0, 0            # 0 = false
+    ret
+3:
+    li a0, 1            # 1 = true
+    ret