Updated init.S file, updated Makefile for thumb instructions

Author: drichmond

riscvonpynq/cortexm1/tcm/build/init.S

@@ -1,7 +1,6 @@
     .syntax     divided
-
+    .thumb
     .section    .stack
-    .align      3
     #ifdef __STACK_SIZE
         .equ        Stack_Size, (__STACK_SIZE >> 1)
     #else
@@ -22,9 +21,15 @@
 
 
 Reset_Handler:
-    .extern main
-//    ldr r0, =0x10
-//    ldr r1, =0xdeadbeef
-//    str r1, [r0]
-    ldr     r0, =main
-    bx     r0
+	//.extern main
+	mov    r0, #0
+	mov    r1, #0
+	mov    r2, #20
+	str    r0, [r2]
+	mov    r2, #0
+	mov    r3, #0
+	mov    r4, #0
+	mov    r5, #0
+	mov    r6, #0
+	mov    r7, #0
+	//bl     main

riscvonpynq/cortexm1/tcm/build/makefile

@@ -1,15 +1,15 @@
 STKPTR ?= 0x10000
 __STACK_SIZE = $(STKPTR)
-CFLAGS = -Wall --std=c99 -ffreestanding -nostdlib -marm -mtune=cortex-m1
+CFLAGS = -Wall --std=c99 -ffreestanding -nostdlib -mthumb -mcpu=cortex-m1  -msoft-float
 all: $(TARGET).bin
 
 init.o: init.S
 	@echo "Building object file $@ for $<"
-	arm-linux-gnueabihf-gcc -c -Qn -D__STACK_SIZE=$(__STACK_SIZE) -marm -mtune=cortex-m1 $< -o $@ 
+	arm-linux-gnueabihf-gcc -c -Qn -D__STACK_SIZE=$(__STACK_SIZE) $(CFLAGS) $< -o $@ 
 
-%.elf: init.o %.o
+%.elf: init.o  %.o
 	@echo "Combining object files $< to produce $@"
-	gcc -static -ffreestanding -nostdlib -marm -Wl,-Bstatic,-T,cortexm1.ld,--build-id=none \
+	gcc -static $(CFLAGS) -Wl,-Bstatic,-T,cortexm1.ld,--build-id=none \
 		-mtune=cortex-m1 $^ -o $@
 
 %.o: %.c