From: Robin Krens <robin@robinkrens.nl>
Date: Fri, 5 Jul 2019 09:49:05 +0000 (+0800)
Subject: static RAM (.data) usage
X-Git-Url: https://robinkrens.nl/gitweb/?a=commitdiff_plain;h=2dcce7050a791e5b3ff81e9c785d05aa79f57ba0;p=cortex-from-scratch

static RAM (.data) usage
---

diff --git a/Makefile b/Makefile
index cc01e47..2563e88 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,7 @@ as:
 all:
 	$(AS) $(CFLAGS) -o start.o start.asm
 	$(LD) -T link.ld -o start.out start.o
-	$(MKIMG) -Obinary start.out kernel.bin
+	$(MKIMG) -Obinary -R .data start.out kernel.bin
 
 run:
 	qemu-system-arm	-monitor stdio -M lm3s6965evb -kernel kernel.bin
diff --git a/link.ld b/link.ld
index 00ce90e..903f1f5 100644
--- a/link.ld
+++ b/link.ld
@@ -1,6 +1,6 @@
 MEMORY
 {
-	FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 512K
+	FLASH (xr) : ORIGIN = 0x00000000, LENGTH = 512K
 	SRAM (xrw) : ORIGIN = 0x20000000, LENGTH = 64K
 }
 
diff --git a/start.asm b/start.asm
index 8991594..8af6fea 100644
--- a/start.asm
+++ b/start.asm
@@ -9,14 +9,23 @@ _start:
 
 /* Start of main program */
 start:
-	movs r0, #10
-	movs r1, #5
+	movs r0, #5
+	movs r1, #1
 loop:
 	adds r1, r0
 	subs r0, #1
 	bne loop
-/* Result is now in R1 */
+	/* Result is now in R1 */
+	ldr r0, =Result
+	str r1, [r0] 
+
 deadloop:
 	b deadloop
+
+	.data
+	.word 0 /* add two words*/
+	.word 0 
+Result:
+	.word 0 /* results now is in 0x20000008 (0x20000000 + 2 w) */
 	.end