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dwelch67dwelch67
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added thumb assembler example, this is not part of an asm tutorial just
testing the new thumb assembler mods.
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‎tas/README

+18-13
Original file line numberDiff line numberDiff line change
@@ -3,20 +3,25 @@ This is a thumb assembler derived directly from the assembler in my
33
thumbulator project. The thumulator version remains the primary
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version/home.
55

6-
I added some hardcoded machine code up front to get from arm to thumb
7-
and then if you bl hexstring, I tack on machine code to implement that
8-
function. hexstring takes r0 and prints it out on the uart in ascii.
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I added the .include directive in the original thumbulator this one has
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a base address, still flushing that out.
98

10-
Since I got it working I dont want to just discard it, but not sure
11-
what I want to do with this...I provided binaries for the bootloaders
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so that you dont have to have arm tools, which is why you would use tas
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because you want to try asm but dont want to try or have failed to build
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gnu binutils. tas should build most anywhere.
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This is headed towards a learn assembly tutorial using this easy to
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compile tool if building binutils is not working for you or too
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intimidating right now. Also binutils separates assemble and link
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and linker scripts are a programming language themselves.
1513

16-
One simple test program provided, thats it
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by adding .include things like the little bit of arm code needed to
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get you into thumb mode. And a pre-compiled implementation of hexstring
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and uart_init so you dont have to have tools or understand how that
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code works to get started in the environment I invision for a learn
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asm tutorial.
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18-
./tas test.s
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If you dont have anything to talk to the uart (see top level readme)
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then the blinker example should work at a minimum
1922

20-
then use a bootloader to load test.s.bin. Since the test program + tas
21-
require the mini uart to be initialized simply copying test.s.bin to
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kernel.img wont do you any good.
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./tas blinker01.s
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gives you blinker01.s.bin which you should be able to copy to kernel.img
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on your sd card and when you power cycle it should come up and blink the
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led.

‎tas/armstart.s

+43-15
Original file line numberDiff line numberDiff line change
@@ -1,18 +1,46 @@
11

2-
.globl _start
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_start:
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b reset
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reset:
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ldr sp,stack_start
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ldr r0,thumb_start_add
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bx r0
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; 00000000 <_start>:
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; 0: eaffffff b 4 <reset>
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;
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; 00000004 <reset>:
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; 4: e59fd004 ldr sp, [pc, #4] ; 10 <stack_start>
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; 8: e59f0004 ldr r0, [pc, #4] ; 14 <thumb_start_add>
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; c: e12fff10 bx r0
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;
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; 00000010 <stack_start>:
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; 10: 08000000
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;
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; 00000014 <thumb_start_add>:
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; 14: 00000021
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; 18: 00000000
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; 1C: 00000000
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;
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; 00000020 <thumb_start>:
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;
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;0x00000000
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.hword 0xFFFF
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.hword 0xEAFF
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;0x00000004
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.hword 0xD004
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.hword 0xE59F
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;0x00000008
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.hword 0x0004
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.hword 0xE59F
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;0x0000000C
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.hword 0xFF10
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.hword 0xE12F
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;0x00000010
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.hword 0x0000
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.hword 0x0800
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;0x00000014
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.hword 0x8021
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.hword 0x0000
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;0x00000018
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.hword 0x0000
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.hword 0x0000
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;0x0000001C
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.hword 0x0000
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.hword 0x0000
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;0x00000020
945

10-
stack_start: .word 0x1000
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thumb_start_add: .word thumb_start
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.word 0
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.word 0
1446

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.thumb
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.thumb_func
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thumb_start:
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b .

‎tas/armstart_source.s

+18
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
2+
.globl _start
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_start:
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b reset
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reset:
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ldr sp,stack_start
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ldr r0,thumb_start_add
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bx r0
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stack_start: .word 0x1000
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thumb_start_add: .word thumb_start
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.word 0
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.word 0
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.thumb
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.thumb_func
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thumb_start:
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b .

‎tas/blinker01.s

+44
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,44 @@
1+
2+
.include armstart.s
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;configure gpio as an output
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ldr r0,GPFSEL1
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ldr r1,[r0]
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;ra&=~(7<<18); zero bits 18,19,20
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mov r2,#0x7
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lsl r2,r2,#18
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bic r1,r2
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;ra|=1<<18; set bit 18
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mov r2,#0x1
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lsl r2,r2,#18
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orr r1,r2
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str r1,[r0]
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;prepare registers for loop
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ldr r0,GPSET0
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ldr r1,GPCLR0
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mov r2,#1
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lsl r3,r2,#16 ;(1<<16)
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lsl r4,r2,#24 ;start count for counting loop
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top:
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str r3,[r0]
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27+
mov r5,r4
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on:
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sub r5,#1
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bne on
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str r3,[r1]
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34+
mov r5,r4
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off:
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sub r5,#1
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bne off
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b top
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.align
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GPFSEL1: .word 0x20200004
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GPSET0: .word 0x2020001C
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GPCLR0: .word 0x20200028

‎tas/hexstring.s

+46
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,46 @@
1+
.align
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hexstring:
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.hword 0xB5FE;
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.hword 0x4913;
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.hword 0x4e13;
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.hword 0x2420;
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.hword 0x270f;
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.hword 0x2220;
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.hword 0x3c04;
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.hword 0x1c03;
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.hword 0x40e3;
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.hword 0x403b;
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.hword 0x1c1d;
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.hword 0x3530;
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.hword 0x2b09;
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.hword 0xd900;
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.hword 0x3507;
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.hword 0x680b;
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.hword 0x421a;
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.hword 0xd0fc;
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.hword 0x6035;
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.hword 0x2c00;
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.hword 0xd1f0;
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.hword 0x4909;
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.hword 0x2220;
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.hword 0x680b;
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.hword 0x421a;
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.hword 0xd0fc;
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.hword 0x4b07;
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.hword 0x220d;
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.hword 0x4905;
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.hword 0x601a;
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.hword 0x2220;
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.hword 0x680b;
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.hword 0x421a;
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.hword 0xd0fc;
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.hword 0x4b03;
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.hword 0x220a;
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.hword 0x601a;
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.hword 0xbcfe;
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.hword 0xbc01;
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.hword 0x4700;
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.hword 0x5054;
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.hword 0x2021;
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.hword 0x5040;
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.hword 0x2021;

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