3_test/uartint.s

   1 .data
   2 str:
   3         .fill 0x41424344
   4         .fill 0x0a0d0000
   5 .text
   6         .define UART_BASE, 0x2000
   7         .define UART_STATUS, 0x0
   8         .define UART_RECV, 0xc
   9         .define UART_TRANS, 0x8
  10
  11         .define UART_TRANS_EMPTY, 0x1
  12         .define UART_RECV_NEW, 0x2
  13 start:
  14         br+ main ;br+
  15         br+ main
  16         ret
  17 main:
  18         ldi r10, UART_BASE@lo
  19         ldih r10, UART_BASE@hi
  20         ldw r5, UART_STATUS(r10)
  21         andx r5, UART_RECV_NEW
  22         brzs+ main ; no new data?
  23         ldw r7, UART_RECV(r10) ; load data
  24
  25         xor r1, r1, r1
  26         xor r2, r2, r2
  27         xor r3, r3, r3
  28         ; ldi r1, str
  29         ; ldi r1, 0x58
  30         ; stb r1, str(r3)
  31         ldw r1, str(r3)
  32         ldi r2, 6
  33         ;call send_string
  34         call send_byte
  35
  36 main2:
  37         ldw r5, UART_STATUS(r10)
  38         andx r5, UART_RECV_NEW
  39         brzs+ main2 ; no new data?
  40         ldw r7, UART_RECV(r10) ; load data
  41 uartnrdy:
  42         ldw r5, 0(r0)
  43         andx r5, UART_TRANS_EMPTY
  44         brnz+ uartnrdy ; transmitter not ready yet?
  45         stw r7, UART_TRANS(r10) ; send zeh shit!
  46         br main2 ; back to usual stuff
  47
  48 send_string:
  49         ; r1 = addr
  50         ; r2 = len
  51         addi r3, r1, 0
  52 send_string_int:
  53         cmpi r2, 0
  54         reteq-
  55         ldb r1, 0(r3)
  56         call send_byte
  57         addi r2, r2, 0-1
  58         addi r3, r3, 1
  59         br send_string_int
  60
  61 send_byte:
  62         ldw r9, UART_STATUS(r10)
  63         andx r9, UART_TRANS_EMPTY
  64         brnz+ send_byte ; branch if not zero
  65         stw r1, UART_TRANS(r10)
  66         ret