mbed LPC1768 pyLLVM GPIO

boot.s

/* Boot stub. Must be linked first to be at the beginning of the program ROM. */
/* Main program must provide an entry point function called "main". */

.cpu cortex-m3
.thumb

.word   0x10008000  /* stack top address */
.word   _start      /* 1 Reset */
.word   hang        /* 2 NMI */
.word   hang        /* 3 HardFault */
.word   hang        /* 4 MemManage */
.word   hang        /* 5 BusFault */
.word   hang        /* 6 UsageFault */
.word   hang        /* 7 RESERVED */
.word   hang        /* 8 RESERVED */
.word   hang        /* 9 RESERVED*/
.word   hang        /* 10 RESERVED */
.word   hang        /* 11 SVCall */
.word   hang        /* 12 Debug Monitor */
.word   hang        /* 13 RESERVED */
.word   hang        /* 14 PendSV */
.word   hang        /* 15 SysTick */
.word   hang        /* 16 External Interrupt(0) */
.word   hang        /* 17 External Interrupt(1) */
.word   hang        /* 18 External Interrupt(2) */
.word   hang        /* 19 ...   */

.thumb_func
hang:   b .

.thumb_func
.globl _start
_start:
        bl main
        bl hang

.end

genblink.py

#!/usr/bin/env python

from llvm import *
from llvm.core import *

module = Module.new('blink')

ty_void = Type.void()
ty_int32 = Type.int(32)
ty_int32_ptr = Type.pointer(ty_int32)

ty_f_main = Type.function(ty_void, [])
f_main = module.add_function(ty_f_main, "main")

bb = f_main.append_basic_block("entry")

builder = Builder.new(bb)

# OK, now for the instructions themselves. We'll create an add
# instruction that returns the sum as a value, which we'll use
# a ret instruction to return.
#tmp = builder.add(f_sum.args[0], f_sum.args[1], "tmp")
#builder.ret(tmp)

reg_direction = builder.inttoptr(
    Constant.int(ty_int32, 537509922),
    ty_int32_ptr,
)
# LPC1768 GPIOs have both a basic value register, allowing the
# port to be read and written as a single integer, and special
# set/clear registers that will set/clear (respectively) any
# bit set to 1 when written, leaving any 0 bits unchanged.
# This allows individual bits to be modified without having to
# read and preserve the other bits.
reg_clear = builder.inttoptr(
    Constant.int(ty_int32, 537509950),
    ty_int32_ptr,
)
reg_set = builder.inttoptr(
    Constant.int(ty_int32, 537509946),
    ty_int32_ptr,
)

# Set the LED pin to be an output.
builder.store(
    Constant.int(ty_int32, 128),
    reg_direction,
    volatile=True,
)
# Clear LED pin.
builder.store(
    Constant.int(ty_int32, 128),
    reg_clear,
    volatile=True,
)
# Set LED pin.
builder.store(
    Constant.int(ty_int32, 128),
    reg_set,
    volatile=True,
)

builder.ret_void()

# We've completed the definition now! Let's see the LLVM assembly
# language representation of what we've created:
print module

linker

/* GCC Linker Script */
MEMORY
{
   rom(RX)   : ORIGIN = 0x00000000, LENGTH = 0x40000
   ram(WAIL) : ORIGIN = 0x10000000, LENGTH = 30K
}

SECTIONS
{
   .text : { *(.text*) } > rom
   .bss  : { *(.bss*) } > ram
}

Makefile

all: blink.bin

blink.ll: genblink.py
	python genblink.py >blink.ll

blink.bc: blink.ll
	opt-3.4 blink.ll -o blink.bc

blink.s: blink.bc
	llc-3.4 -march=thumb blink.bc -o blink.s

%.o: %.s
	arm-none-eabi-as $< -o $@

blink.elf: boot.o blink.o
	arm-none-eabi-ld -T linker boot.o blink.o -o blink.elf

blink.bin: blink.elf
	arm-none-eabi-objcopy blink.elf blink.bin -O binary

clean:
	rm -f blink.ll blink.s blink.o boot.o blink.elf blink.bin blink.bc

upload: blink.bin
	cp blink.bin /media/MBED/blink.bin