From: Bernhard Urban <lewurm@gmail.com>
Date: Tue, 26 Oct 2010 18:29:59 +0000 (+0200)
Subject: isa/examples: minor fixes at bootrom.s
X-Git-Tag: bootrom_v1~253
X-Git-Url: http://wien.tomnetworks.com/gitweb/?p=calu.git;a=commitdiff_plain;h=5a92a4cb0b3bff34af40c6f2f0faf0be34bb28e0

isa/examples: minor fixes at bootrom.s
---

diff --git a/2_isa/src/bootrom.s b/2_isa/src/bootrom.s
index 9ae2570..13e4e45 100644
--- a/2_isa/src/bootrom.s
+++ b/2_isa/src/bootrom.s
@@ -17,9 +17,44 @@
 	UART_TRANS_EMPTY=0
 	UART_RECV_NEW=1
 
+	TIMEOUT_START=0x13371337
+	DEFAULT_PROG_START=0x200
+	STACKSTART=0x500 ; FIXME
+;-----
+main:
+	; setup stackframe
+	ldil r15, STACKSTART@lo
+	ldih r15, STACKSTART@hi
+
+	ldil r3, TIMEOUT_START@lo
+	ldih r3, TIMEOUT_START@hi
+
+timeout_loop:
+	ldil r3, UART_STATUS@lo
+	ldih r3, UART_STATUS@hi
+	ldw r3, 0(r3)
+	andi r3, r3, 1 << UART_RECV_NEW
+	jumpzs+ next; jump if zero
+
+	branch recv_byte
+	; we received the enter bootrom sign
+	cmp r0, 0x48 ; 'H'
+	jumpeq- bt_H
+
+next:
+	subi r3, r3, 1
+	jumpnz+ timeout_loop
+
+	; branch to default entry point
+	ldil r0, DEFAULT_PROG_START@lo
+	ldih r0, DEFAULT_PROG_START@hi
+	jumpreg r0
+
+;-----
 send_byte:
 	ldil r3, UART_STATUS@lo	
 	ldih r3, UART_STATUS@hi
+	ldw r3, 0(r3)
 	andi r3, r3, 1 << UART_TRANS_EMPTY
 	jumpzs+ send_byte ; jump if zero
 	ldil r3, UART_TRANS@lo	
@@ -27,6 +62,7 @@ send_byte:
 	stb r0, 0(r3)
 	ret
 
+;-----
 send_word:
 	; TODO: loop? (less codesize...)
 	branch send_byte
@@ -38,9 +74,11 @@ send_word:
 	branch send_byte
 	ret
 
+;-----
 recv_byte:
 	ldil r3, UART_STATUS@lo	
 	ldih r3, UART_STATUS@hi
+	ldw r3, 0(r3)
 	andi r3, r3, 1 << UART_RECV_NEW
 	jumpzs+ send_byte ; jump if zero
 	ldil r3, UART_RECV@lo	
@@ -48,6 +86,7 @@ recv_byte:
 	lwb r0, 0(r3)
 	ret
 
+;-----
 recv_word:
 	ldil r1, 0x0 
 	branch recv_byte
@@ -69,6 +108,7 @@ recv_word:
 	ret
 
 
+;-----
 bootrom:
 	branch recv_byte
 
@@ -136,36 +176,4 @@ bt_J:
 	branch recv_word
 	jumpreg r0
 
-	
-	TIMEOUT_START=0x13371337
-	DEFAULT_PROG_START=0x200
-	STACKSTART=0x500 ; FIXME
-main:
-	; setup stackframe
-	ldil r15, STACKSTART@lo	
-	ldih r15, STACKSTART@hi
-
-	ldil r3, TIMEOUT_START@lo	
-	ldih r3, TIMEOUT_START@hi
-
-timeout_loop:
-	ldil r3, UART_STATUS@lo	
-	ldih r3, UART_STATUS@hi
-	andi r3, r3, 1 << UART_RECV_NEW
-	jumpzs+ next; jump if zero
-
-	branch recv_byte
-	; we received the enter bootrom sign
-	cmp r0, 0x48 ; 'H'
-	jumpeq- bt_H
-
-next:
-	subi r3, r3, 1
-	jumpnz+ timeout_loop
-	
-	; branch to default entry point
-	ldil r0, DEFAULT_PROG_START@lo	
-	ldih r0, DEFAULT_PROG_START@hi
-	jumpreg r0
-
-; 99 instr. please update after modification
+; 101 instr. please update after modification