Newbie want to learn Assembly on Raspberry Pi B 2.0 running Debian

Hi krynobosman and welcome to the community!

Though I don't have a RasPi myself and can't recommend any books, I'm programming in assembly language myself on the Cortex-M.

I have a CubieBoard2 running Cubian Linux, which I use for testing Cortex-M code (it can be compiled and run on the Cortex-A), thus my environment would be similar to yours.

What I use is GCC-4.7.2 (the default compiler for Cubian), and I've made a few tests in assembly language. I run these programs on the command-line (via SSH).

First of all, I recommend that you go to the ARM Information Center and download the ARMv7AR Reference Manual.

Because the Cortex-M User Guides are so easy/quick to read, I also suggest that you take a look at the Cortex-M4 instruction set, because it gives you a quick overview of each instruction. Also the Table of Processor Instructions might be interesting. This should give you a quick start.

-But of course, your Cortex-A7 based Raspberry Pi can do much more than the Cortex-M4, so you'll also be interested in GPU and vector programming.

Since I don't know any books myself, I'll let other people recommend books; you may want to follow people like peterharris, daith, jyiu and chrisshore (though Joseph is a Cortex-M expert, he oftens answers questions about or related to assembly language, and his answers gives a good understanding on how the ARM architecture works).

In addition, I'd like to post a small quick-start on how you can compile a minimal assembly language program on the command-line.

This example shows you a few things; including how to build without writing a Makefile, how to call functions written in assembly language from C and how to call C functions from assembly language (including that parameters are passed in registers):

File: 'b'. After saving, issue a 'chmod 755 b' command:

#!/bin/bash

DEVICE="cortex-a7"
DEV_FLAGS="-mcpu=${DEVICE} -mtune=${DEVICE}"
FLAGS="${DEV_FLAGS} -mthumb"
ASFLAGS="${FLAGS} -Wa,-mimplicit-it=always -x assembler-with-cpp"
GCFLAGS="${FLAGS} -mthumb-interwork -Wall -Wextra -Wimplicit -Wcast-align -Wpointer-arith -Wredundant-decls -Wshadow -Wcast-qual -Wcast-align -Wnested-externs --std=gnu99"
LDFLAGS="${FLAGS} -lc -lm -lgcc -lstdc++"

gcc ${GCFLAGS} -c main.c -o main.o && \
gcc ${ASFLAGS} -c example.s -o example.o && \
g++ ${LDFLAGS} *.o -o example && \
./example

File: 'main.c':

#include <stdint.h>
#include <stdio.h>

void example(void);

int main(int argc, const char *argv[])
{
  example();
  return(0);
}

File: 'example.s'

                    .syntax             unified             /* use modern syntax */
                    .text                                   /* place our code in the text-section */

                    .func               example             /* (for debugging info) */
                    .global             example             /* make 'example' symbol global */
                    .type               example,%function   /* 'example' is a function */
                    .thumb_func                             /* a function, which uses thumb instructions */

example:            push                {r4-r7,lr}          /* save r4-r7 and return address */
                    ldr                 r0,=string          /* point to format string */
                    movs                r1,#1               /* parameter 1 value */
                    movw                r2,#777             /* parameter 2 value */
                    bl                  printf              /* call printf */
                    pop                 {r4-r7,pc}          /* restore saved registers and return */
                    .pool                                   /* allow the assembler to place a literal pool here */
                    .size               example,.-example   /* tell linker how large this function is */
string:             .asciz              "Value 1:%ld \nValue 2:%ld\n"     /* a format-string for printf */

                    .endfunc                                /* (for debugging info) */

To build, just type ./b on the command-line. The files should then be compiled and executed.

Hi krynobosman and welcome to the community!

Though I don't have a RasPi myself and can't recommend any books, I'm programming in assembly language myself on the Cortex-M.

I have a CubieBoard2 running Cubian Linux, which I use for testing Cortex-M code (it can be compiled and run on the Cortex-A), thus my environment would be similar to yours.

What I use is GCC-4.7.2 (the default compiler for Cubian), and I've made a few tests in assembly language. I run these programs on the command-line (via SSH).

First of all, I recommend that you go to the ARM Information Center and download the ARMv7AR Reference Manual.

Because the Cortex-M User Guides are so easy/quick to read, I also suggest that you take a look at the Cortex-M4 instruction set, because it gives you a quick overview of each instruction. Also the Table of Processor Instructions might be interesting. This should give you a quick start.

-But of course, your Cortex-A7 based Raspberry Pi can do much more than the Cortex-M4, so you'll also be interested in GPU and vector programming.

Since I don't know any books myself, I'll let other people recommend books; you may want to follow people like peterharris, daith, jyiu and chrisshore (though Joseph is a Cortex-M expert, he oftens answers questions about or related to assembly language, and his answers gives a good understanding on how the ARM architecture works).

In addition, I'd like to post a small quick-start on how you can compile a minimal assembly language program on the command-line.

This example shows you a few things; including how to build without writing a Makefile, how to call functions written in assembly language from C and how to call C functions from assembly language (including that parameters are passed in registers):

File: 'b'. After saving, issue a 'chmod 755 b' command:

#!/bin/bash

DEVICE="cortex-a7"
DEV_FLAGS="-mcpu=${DEVICE} -mtune=${DEVICE}"
FLAGS="${DEV_FLAGS} -mthumb"
ASFLAGS="${FLAGS} -Wa,-mimplicit-it=always -x assembler-with-cpp"
GCFLAGS="${FLAGS} -mthumb-interwork -Wall -Wextra -Wimplicit -Wcast-align -Wpointer-arith -Wredundant-decls -Wshadow -Wcast-qual -Wcast-align -Wnested-externs --std=gnu99"
LDFLAGS="${FLAGS} -lc -lm -lgcc -lstdc++"

gcc ${GCFLAGS} -c main.c -o main.o && \
gcc ${ASFLAGS} -c example.s -o example.o && \
g++ ${LDFLAGS} *.o -o example && \
./example

File: 'main.c':

#include <stdint.h>
#include <stdio.h>

void example(void);

int main(int argc, const char *argv[])
{
  example();
  return(0);
}

File: 'example.s'

                    .syntax             unified             /* use modern syntax */
                    .text                                   /* place our code in the text-section */

                    .func               example             /* (for debugging info) */
                    .global             example             /* make 'example' symbol global */
                    .type               example,%function   /* 'example' is a function */
                    .thumb_func                             /* a function, which uses thumb instructions */

example:            push                {r4-r7,lr}          /* save r4-r7 and return address */
                    ldr                 r0,=string          /* point to format string */
                    movs                r1,#1               /* parameter 1 value */
                    movw                r2,#777             /* parameter 2 value */
                    bl                  printf              /* call printf */
                    pop                 {r4-r7,pc}          /* restore saved registers and return */
                    .pool                                   /* allow the assembler to place a literal pool here */
                    .size               example,.-example   /* tell linker how large this function is */
string:             .asciz              "Value 1:%ld \nValue 2:%ld\n"     /* a format-string for printf */

                    .endfunc                                /* (for debugging info) */

To build, just type ./b on the command-line. The files should then be compiled and executed.