bootromfun: okay, speicherzugriffe haben definitiv bei mein fpga ned [...]

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

diff --git a/2_isa/src/bootrom.s b/2_isa/src/bootrom.s
index dc484d7fea490ffa0b0b5d321494cba2ea36319d..9ff1bf77d26158c56366cccb50566fb1be858a76 100644 (file)
--- a/2_isa/src/bootrom.s
+++ b/2_isa/src/bootrom.s
@@ -9,6 +9,10 @@
        .define UART_TRANS_EMPTY, 0x1
        .define UART_RECV_NEW, 0x2
 
+       .define PBASE, 0x2030
+       .define PADDR, 0x4
+       .define PDATA, 0x8
+
 ;-----
 start:
        br+ main
@@ -18,16 +22,14 @@ start:
 main:
        ldi r10, UART_BASE@lo
        ldih r10, UART_BASE@hi
+       ldi r11, PBASE@lo
+       ldih r11, PBASE@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
+       breq+ bt_H
        br poll ; else
 
 ;-----
@@ -35,7 +37,7 @@ send_byte:
        ldw r3, UART_STATUS(r10)
        andx r3, UART_TRANS_EMPTY
        brnz+ send_byte ; branch if not zero
-       stb r1, UART_TRANS(r10)
+       stw r1, UART_TRANS(r10)
        ret
 
 ;-----
@@ -56,12 +58,11 @@ recv_byte:
        andx r3, UART_RECV_NEW
        brzs+ recv_byte; branch if zero
        xor r0, r0, r0
-       ldb r0, UART_RECV(r10)
+       ldw r0, UART_RECV(r10)
        ret
 
 ;-----
 recv_word:
-       xor r0, r0, r0
        xor r1, r1, r1
        call recv_byte
        or r1, r0, r1
@@ -79,13 +80,14 @@ recv_word:
        or r1, r0, r1
 
        addi r0, r1, 0
-
        ret
 
 ;-----
 bootrom:
-       br tehend
        call recv_byte
+       ldi r1, 0x50 ; 'P'
+       call send_byte
+       br tehend
 
        xor r1, r1, r1
        cmpi r0, 0x57 ; 'W'
@@ -110,14 +112,16 @@ bootrom:
 bt_H:
        ldi r1, 0x4f ; 'O'
        call send_byte
-       ; br bootrom ; FIXME
-       br tehend
+       xor r1, r1, r1
+       ldi r1, 0x41 ; 'A'
+       call send_byte
+       br bootrom
 
 bt_W:
        call recv_word ; receive addr
-       mov r6, r0
+       stw r0, PADDR(r11)
        call recv_word ; receive instr
-       stx r0, 0(r6)
+       stw r0, PDATA(r11)
        ldi r1, 0x44 ; 'D'
        call send_byte
        br bootrom
@@ -154,3 +158,12 @@ bt_J:
        brr r0
 
 tehend:
+       xor r1, r1, r1
+       ldi r1, 0x41 ; 'A'
+       call send_byte
+       xor r1, r1, r1
+       ldi r1, 0x42 ; 'B'
+       call send_byte
+       xor r1, r1, r1
+       ldi r1, 0x43 ; 'C'
+       call send_byte