bootromfun/dtprog: programmer fuers BootROM \o/

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

diff --git a/2_isa/src/bootrom.s b/2_isa/src/bootrom.s
index 87b7f83f1a508bbd913707b723f90962ada6ad48..bfc81890abd408ba06dc782e3e5249a2b978ad45 100644 (file)
--- a/2_isa/src/bootrom.s
+++ b/2_isa/src/bootrom.s
@@ -1,3 +1,29 @@
+;* bootROM, a very small bootloader for $NAME
+;*
+;* protocol details:
+;* abbrv: H = Host, CPU = C
+;*
+;* value/cmd              | direction | comment
+;* ------------------------------------------------------------
+;* 'H'                    | H -> C    | enter bootROM ("HI")
+;* 'O'                    | C -> H    | ack bootROM entry ("OH HAI")
+;*
+;* 'W'0xZZZZZZZZ0xYYYYYYYY| H -> C    | write instr (0xYY...Y) to
+;*                                    | address (0xZZ...Z)
+;* 'D'                    | C -> H    | instr write done
+;*
+;* 'R'0xZZZZZZZZ          | H -> C    | read instr from address (0xZZ..Z)
+;* 'F'0xYYYYYYYY          | C -> H    | instr read done and return instr
+;*
+;* 'Q'0xZZZZZZZZ0xYYYYYYYY| H -> C    | write data (0xYY...Y) to
+;*                                    | address (0xZZ...Z)
+;* 'A'                    | C -> H    | data write done
+;*
+;* 'T'0xZZZZZZZZ          | H -> C    | read data from address (0xZZ..Z)
+;* 'G'0xYYYYYYYY          | C -> H    | read done and return data
+;*
+;* 'J'0xZZZZZZZZ          | H -> C    | jump to address (0xZZ...Z)
+;*/
        .data
 
        .text
@@ -77,9 +103,9 @@ recv_word:
 
        call recv_byte
        lls r1, r1, 8
-       or r1, r0, r1
+       or r0, r0, r1
+       xor r1, r1, r1
 
-       addi r0, r1, 0
        ret
 
 ;-----
@@ -90,8 +116,8 @@ bootrom:
        cmpi r0, 0x57 ; 'W'
        breq- bt_W
 
-       cmpi r0, 0x52 ; 'R'
-       breq- bt_R
+       ;cmpi r0, 0x52 ; 'R'
+       ;breq- bt_R
 
        cmpi r0, 0x51 ; 'Q'
        breq- bt_Q
@@ -112,15 +138,17 @@ bt_H:
        br bootrom
 
 bt_W:
-       ; call recv_word ; receive addr
-       ; stw r0, PADDR(r11)
-       ; call recv_word ; receive instr
-       ; stw r0, PDATA(r11)
-       ; ldi r1, 0x44 ; 'D'
-       ; call send_byte
+       ldi r1, 0x57 ; 'W'
+       call send_byte
+       call recv_word ; receive addr
+       stw r0, PADDR(r11)
+       call recv_word ; receive instr
+       stw r0, PDATA(r11)
+       ldi r1, 0x44 ; 'D'
+       call send_byte
        br bootrom
 
-bt_R:
+;bt_R: ;lesen von IRAM wird nicht unterstuetzt
        ;call recv_word ; receive addr
        ;mov r2, r0
        ;ldi r1, 0x46 ; 'F'
@@ -128,11 +156,12 @@ bt_R:
        ;ldx r1, 0(r2)
        ;call send_word
        ;br bootrom
-       br tehend
 
 bt_Q:
+       ldi r1, 0x51 ; 'Q'
+       call send_byte
        call recv_word ; receive addr
-       mov r6, r0
+       addi r6, r0, 0
        call recv_word ; receive data
        stw r0, 0(r6)
        ldi r1, 0x41 ; 'A'
@@ -149,9 +178,6 @@ bt_T:
        br bootrom
 
 bt_J:
-       call recv_word
-       brr r0
-
 tehend:
        xor r1, r1, r1
        ldi r1, 0x41 ; 'A'