bootromfun: wir kriegen ein 'O' \o/ (wenn man ein 'H' aufn UART schreibt)

[calu.git] / 2_isa / src / bootrom.s

diff --git a/2_isa/src/bootrom.s b/2_isa/src/bootrom.s
index a18b1a68c6713e1432a9d14e9621b54a87c046d9..dc484d7fea490ffa0b0b5d321494cba2ea36319d 100644 (file)
--- a/2_isa/src/bootrom.s
+++ b/2_isa/src/bootrom.s
@@ -1,59 +1,41 @@
        .data
 
        .text
-       .define UART_BASE, 0x1000
-       .define UART_STATUS, UART_BASE+0x4
-       .define UART_RECV, UART_BASE+0x8
-       .define UART_TRANS, UART_BASE+0xC
-       .define UART_BAUD, UART_BASE+0x10
-
-       .define UART_TRANS_EMPTY, 0
-       .define UART_RECV_NEW, 1
-
-       .define TIMEOUT_START, 0x13371337
-       .define DEFAULT_PROG_START, 0x200
-       .define STACKSTART, 0x500 ; FIXME
-;-----
-main:
-       ; setup stackframe
-       ldil r15, STACKSTART@lo
-       ldih r15, STACKSTART@hi
-       movst r15
+       .define UART_BASE, 0x2000
+       .define UART_STATUS, 0x0
+       .define UART_RECV, 0xc
+       .define UART_TRANS, 0x8
 
-       ldil r3, TIMEOUT_START@lo
-       ldih r3, TIMEOUT_START@hi
+       .define UART_TRANS_EMPTY, 0x1
+       .define UART_RECV_NEW, 0x2
 
-timeout_loop:
-       ldil r3, UART_STATUS@lo
-       ldih r3, UART_STATUS@hi
-       ldw r3, 0(r3)
-       andx r3, 1 << UART_RECV_NEW
-       brzs+ next; branch if zero
+;-----
+start:
+       br+ main
+       br+ main
+       ret
+
+main:
+       ldi r10, UART_BASE@lo
+       ldih r10, UART_BASE@hi
+poll:
+       ldw r3, UART_STATUS(r10)
+       andx r3, UART_RECV_NEW
+       brzs+ poll; branch if zero
 
        call recv_byte
        ; we received the enter bootrom sign
+       xor r1, r1, r1
        cmpi r0, 0x48 ; 'H'
        breq- bt_H
-
-next:
-       subi r3, r3, 1
-       brnz+ timeout_loop
-
-       ; call to default entry point
-       ldil r0, DEFAULT_PROG_START@lo
-       ldih r0, DEFAULT_PROG_START@hi
-       brr r0
+       br poll ; else
 
 ;-----
 send_byte:
-       ldil r3, UART_STATUS@lo 
-       ldih r3, UART_STATUS@hi
-       ldw r3, 0(r3)
-       andx r3, 1 << UART_TRANS_EMPTY
-       brzs+ send_byte ; branch if zero
-       ldil r3, UART_TRANS@lo  
-       ldih r3, UART_TRANS@hi
-       stb r1, 0(r3)
+       ldw r3, UART_STATUS(r10)
+       andx r3, UART_TRANS_EMPTY
+       brnz+ send_byte ; branch if not zero
+       stb r1, UART_TRANS(r10)
        ret
 
 ;-----
@@ -70,40 +52,42 @@ send_word:
 
 ;-----
 recv_byte:
-       ldil r3, UART_STATUS@lo 
-       ldih r3, UART_STATUS@hi
-       ldw r3, 0(r3)
-       andx r3, 1 << UART_RECV_NEW
-       brzs+ send_byte ; branch if zero
-       ldil r3, UART_RECV@lo   
-       ldih r3, UART_RECV@hi
-       ldb r0, 0(r3)
+       ldw r3, UART_STATUS(r10)
+       andx r3, UART_RECV_NEW
+       brzs+ recv_byte; branch if zero
+       xor r0, r0, r0
+       ldb r0, UART_RECV(r10)
        ret
 
 ;-----
 recv_word:
-       ldisl r0, 0x0
+       xor r0, r0, r0
+       xor r1, r1, r1
        call recv_byte
-       or r0, r0, r1
+       or r1, r0, r1
 
        call recv_byte
        lls r1, r1, 8
-       or r0, r0, r1
+       or r1, r0, r1
 
        call recv_byte
-       lls r1, r1, 16
-       or r0, r0, r1
+       lls r1, r1, 8
+       or r1, r0, r1
 
        call recv_byte
-       lls r1, r1, 24
-       or r0, r0, r1
+       lls r1, r1, 8
+       or r1, r0, r1
+
+       addi r0, r1, 0
 
        ret
 
 ;-----
 bootrom:
+       br tehend
        call recv_byte
 
+       xor r1, r1, r1
        cmpi r0, 0x57 ; 'W'
        breq- bt_W
 
@@ -124,23 +108,24 @@ bootrom:
        ; FALL THROUGH ;)
 
 bt_H:
-       ldisl r1, 0x4f ; 'O'
+       ldi r1, 0x4f ; 'O'
        call send_byte
-       br bootrom
+       ; br bootrom ; FIXME
+       br tehend
 
 bt_W:
        call recv_word ; receive addr
        mov r6, r0
        call recv_word ; receive instr
        stx r0, 0(r6)
-       ldisl r1, 0x44 ; 'D'
+       ldi r1, 0x44 ; 'D'
        call send_byte
        br bootrom
 
 bt_R:
        call recv_word ; receive addr
        mov r2, r0
-       ldisl r1, 0x46 ; 'F'
+       ldi r1, 0x46 ; 'F'
        call send_byte
        ldx r1, 0(r2)
        call send_word
@@ -151,14 +136,14 @@ bt_Q:
        mov r6, r0
        call recv_word ; receive data
        stw r0, 0(r6)
-       ldisl r1, 0x41 ; 'A'
+       ldi r1, 0x41 ; 'A'
        call send_byte
        br bootrom
 
 bt_T:
        call recv_word ; receive addr
        mov r2, r0
-       ldisl r1, 0x47 ; 'G'
+       ldi r1, 0x47 ; 'G'
        call send_byte
        ldw r1, 0(r2)
        call send_word
@@ -168,4 +153,4 @@ bt_J:
        call recv_word
        brr r0
 
-; 102 instr. please update after modification
+tehend: