Unable to compile U2F (chopstx)

[shouya]

Sorry for posting this issue here since im-tomu/chopstx doesn't have an issue tracker.

I was trying to build the u2f source code for my Tomu but the following error prevents it from building the binary:

arm-none-eabi-gcc -c -mcpu=cortex-m0plus -O3 -Os -fstack-usage -ffunction-sections -fdata-sections -fno-common -Wall -Wextra -Wstrict-prototypes -Wa,-alms=build/bn.lst -DMAKE_ENTRY_PUBLIC -DUSE_SYS3 -DFREE_STANDING -DMHZ=21 -mthumb -mno-thumb-interwork -DTHUMB -MD -MP -MF .dep/bn.o.d -I. -I.. bn.c -o build/bn.o
In file included from bn.c:134:0:
bn-thumb1.h: In function ‘bn256_mul_thumb1’:
bn-thumb1.h:32:1: error: ‘asm’ operand has impossible constraints
 asm (                                                      \
 ^
bn-thumb1.h:78:4: note: in expansion of macro ‘MULADD’
    MULADD(at[0], at[8]);
    ^~~~~~

As I checked the source code, MULADD is defined as follows:

#define MULADD(i, j)                                       \
asm (                                                      \
   "ldr r1, %[_i]         \n\t"                            \
   "ldr r2, %[_j]         \n\t"                            \
   "uxth r6, r1           \n\t"                            \
   "uxth r7, r2           \n\t"                            \
   "lsr r1, r1, #16       \n\t"                            \
   "lsr r2, r2, #16       \n\t"                            \
                                                           \
   "mov r0, r6            \n\t"                            \
   "mul r0, r0, r7        \n\t"                            \
   "mul r6, r6, r2        \n\t"                            \
   "mul r2, r2, r1        \n\t"                            \
   "mul r1, r1, r7        \n\t"                            \
                                                           \
   "mov r7, #0            \n\t"                            \
   "add %0, %0, r0        \n\t"                            \
   "adc %1, %1, r2        \n\t"                            \
   "adc %2, %2, r7        \n\t"                            \
                                                           \
   "lsl r0, r6, #16       \n\t"                            \
   "lsr r2, r6, #16       \n\t"                            \
   "add %0, %0, r0        \n\t"                            \
   "adc %1, %1, r2        \n\t"                            \
   "adc %2, %2, r7        \n\t"                            \
                                                           \
   "lsl r0, r1, #16       \n\t"                            \
   "lsr r2, r1, #16       \n\t"                            \
   "add %0, %0, r0        \n\t"                            \
   "adc %1, %1, r2        \n\t"                            \
   "adc %2, %2, r7        \n\t"                            \
                                                           \
   :"=l"(c0), "=l"(c1), "=l"(c2)                           \
   : "0"(c0), "1"(c1), "2"(c2), [_i] "m" (i), [_j] "m" (j) \
   : "r0", "r1", "r2", "r6", "r7", "cc");

I guess it could be some instructions/registers not supported by this chip, but I have no further clue on what to do with it. I have little experience with embedded programming, so I don't know if this situation is very trivial and have simple solutions.

Here's my gcc version:

$ arm-none-eabi-gcc --version
arm-none-eabi-gcc (Gentoo 7.3.0-r3 p1.4) 7.3.0

And my full make log: output.log

A little help would be appreciated!

[shouya]

I'm building it with a clean compiler on a clean system, by following the exact instructions on https://tomu.im/. I've tried compiling some other examples and they all works fine. It only fails for chopstx, for which I guess it could be an issue in this project.

[crazyquark]

Have you tried this:
https://groups.google.com/forum/#!topic/tomu-discuss/HtlArkEWhCo
Towards the end of the thread there is a talk about installing other libnew packages