fixed a couple of emulator bugs, including fixing shift instructions. finished implementing lib/io/print/print_hex_byte and print_hex_word

resources/dsa/lib/io/print.dsa

@@ -82,14 +82,48 @@ print_byte:
 
 // ------------------------------------------
 // prints the value of arg[0] to the screen in hex.
+print_hex_word:
+    push bpr
+    mov spr, bpr
+
+    ldw current, rg1
+
+    ldb bpr, rg0, 8
+    push rg0
+    call _print_hex_byte
+    addi spr, 4
+
+    ldb bpr, rg0, 9
+    push rg0
+    call _print_hex_byte
+    addi spr, 4
+
+    ldb bpr, rg0, 10
+    push rg0
+    call _print_hex_byte
+    addi spr, 4
+
+    ldb bpr, rg0, 11
+    push rg0
+    call _print_hex_byte
+    addi spr, 4
+
+    jmp _end
+
+// ------------------------------------------
+// prints the last byte of arg[0] to the screen in hex.
 print_hex_byte:
     push bpr
     mov spr, bpr
 
-    // put arg byte in rg0
     ldw bpr, rg0, 8
     ldw current, rg1
 
+    call _print_hex_byte
+    jmp _end
+
+// function body
+_print_hex_byte:
     // mask to get lower nibble
     lli 0xF, rg2
     // save rg0 state
@@ -102,8 +136,9 @@ print_hex_byte:
 
     and rg0, rg2, rg0
     call _print_hex_nibble
-    jmp _end
+    return
 
+// print a hex digit
 _print_hex_nibble:
     lli 10, rg3
     cmp rg0, rg3
@@ -111,26 +146,14 @@ _print_hex_nibble:
     addi rg0, 0x37, rg0
     stb rg0, rg1
     addi rg1, 1
-    jmp _end
+    return
 
+// helper function.
 _print_hex_nibble_number:
     addi rg0, 0x30, rg0
     stb rg0, rg1
     addi rg1, 1
-    jmp _end
-
-// ------------------------------------------
-// prints the value of arg[0] to the screen in hex.
-print_hex_word:
-    push bpr
-    mov spr, bpr
-
-    ldw bpr, rg0, 8
-    ldw current, rg1
-
-    stw rg0, rg1
-    addi rg1, 4
-    jmp _end
+    return
 
 // ------------------------------------------
 // resets the cursor position on the screen to 0x20000. (0,0)

resources/dsa/test.dsa

@@ -16,9 +16,9 @@ start:
 	stw rg0, idr, 4
 
 	
-	lli 0x20, rg0
+	lwi 0x1234abcd, rg0
 	push rg0
-	call print::print_hex_byte
+	call print::print_hex_word
 	pop zero
 	hlt