X-Git-Url: http://wien.tomnetworks.com/gitweb/?p=calu.git;a=blobdiff_plain;f=2_isa%2Fsrc%2Fbootrom.s;h=bfc81890abd408ba06dc782e3e5249a2b978ad45;hp=87b7f83f1a508bbd913707b723f90962ada6ad48;hb=5615b8e50fe3adabbdf4da3078245c9e47700ffc;hpb=0e2fe48ee7fc6485bb43090779a506353710a167

diff --git a/2_isa/src/bootrom.s b/2_isa/src/bootrom.s
index 87b7f83..bfc8189 100644
--- 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'