adding thumb assembler, cant decide if I really want this here

Author: dwelch67

tas/Makefile

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+
+tas : tas.c
+	gcc -o tas tas.c
+
+clean : 
+	rm -f tas
+	rm -f *.bin
+	rm -f *.hex
+	rm -f *.s.s
+	rm -f *.s.diss
+
+	

tas/README

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+
+This is a thumb assembler derived directly from the assembler in my
+thumbulator project.  The thumulator version remains the primary
+version/home.
+
+I added some hardcoded machine code up front to get from arm to thumb
+and then if you bl hexstring, I tack on machine code to implement that
+function.  hexstring takes r0 and prints it out on the uart in ascii.
+
+Since I got it working I dont want to just discard it, but not sure
+what I want to do with this...I provided binaries for the bootloaders
+so that you dont have to have arm tools, which is why you would use tas
+because you want to try asm but dont want to try or have failed to build
+gnu binutils.  tas should build most anywhere.
+
+One simple test program provided, thats it
+
+./tas test.s
+
+then use a bootloader to load test.s.bin.  Since the test program + tas
+require the mini uart to be initialized simply copying test.s.bin to
+kernel.img wont do you any good.

tas/armstart.s

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+
+.globl _start
+_start:
+    b reset
+reset:
+    ldr sp,stack_start
+    ldr r0,thumb_start_add
+    bx r0
+
+stack_start: .word 0x1000
+thumb_start_add: .word thumb_start
+.word 0
+.word 0
+
+.thumb
+.thumb_func
+thumb_start:
+    b .

tas/hexstring.c

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+
+void uart_send ( unsigned int );
+void hexstring ( unsigned int d )
+{
+    //unsigned int ra;
+    unsigned int rb;
+    unsigned int rc;
+
+    rb=32;
+    while(1)
+    {
+        rb-=4;
+        rc=(d>>rb)&0xF;
+        if(rc>9) rc+=0x37; else rc+=0x30;
+        uart_send(rc);
+        if(rb==0) break;
+    }
+    uart_send(0x0D);
+    uart_send(0x0A);
+}
+#define AUX_MU_IO_REG   (*((volatile unsigned int *)0x20215040))
+#define AUX_MU_LSR_REG  (*((volatile unsigned int *)0x20215054))
+void uart_send ( unsigned int x )
+{
+    while(1)
+    {
+        if(AUX_MU_LSR_REG&0x20) break;
+    }
+    AUX_MU_IO_REG=x;
+}