Compiler/RM42L432: LDR pseudo instruction replacement

Maciej Sykala

Part Number: RM42L432

Tool/software: TI C/C++ Compiler

Hi,

I'm using CCS9.0 with TI v18.12.1.LTS compiler.

I'm trying to port assembler AES library written for ARM Cortex-M3 and M4 to RM42L432. I am not very experienced in assembler, especially for ARM.

I have a problem with instruction:

ldr.w r12, =AES_Td0

Which loads an array address from AES_Td0 to r12.

I know that it is unsupported pseudo instruction, as per this thread: https://e2e.ti.com/support/tools/ccs/f/81/t/418070.

I wrote the suggested macro as:

LDR_REPLACE .macro dst, src
			movw dst, #(src & 0xffff)
			movt dst, #((src>>16)&0xffff)
			.endm

When I use it as:

    LDR_REPLACE r12, AES_Td0

I get, among others:

- [W1500] warning:  relocation template 267 not found; returning OFR_INVALID
- [E0004] Expression must evaluate to an absolute constant
- [R0001] After symbol substitution the line became:

So relocation is not supported since this macro was suggested i suppose.

I also tried:

movw    dst, #:lower16:src
movt    dst, #:upper16:src

But it also desn't work.

How could i fix this issue?

over 6 years ago

0 Maciej Sykala over 6 years ago

Prodigy 50 points

Perhaps I've asked the question in incorrect subforum? Could the mods move it to the more proper one?

0 Miro over 6 years ago in reply to Maciej Sykala

TI__Mastermind 21425 points

Hello,
Sorry for the delay. I've moved this thread to TI C/C++ Compiler forum.

Best regards,
Miro

0 George Mock over 6 years ago

TI__Guru**** 249260 points

Please show the definition of the symbol AES_Td0.

Thanks and regards,

-George

0 Maciej Sykala over 6 years ago in reply to George Mock

Prodigy 50 points

Hi, AES_Td0 is a big array:

AES_Td0:
	.word 0xf45150a7, 0x417e5365, 0x171ac3a4, 0x273a965e
	.word 0xab3bcb6b, 0x9d1ff145, 0xfaacab58, 0xe34b9303

                                   .
                                   .
                                   .

	.word 0xa8397101, 0x0c08deb3, 0xb4d89ce4, 0x566490c1
	.word 0xcb7b6184, 0x32d570b6, 0x6c48745c, 0xb8d04257

0 George Mock over 6 years ago in reply to Maciej Sykala

TI__Guru**** 249260 points

Try something similar to ...

LDR_REPLACE     .macro dst, src
        .if $$firstch(src,'#')
        LDR_REPLACE  dst, :src(2,$$symlen(src)):
        .elseif $$firstch(src,'=')
        LDR_REPLACE  dst, :src(2,$$symlen(src)):
        .elseif $$iscons(src)
        MOVW dst, #(src >> 16)
        MOVT dst, #(src & 0xffff)
        .else
        MOVW dst, src
        MOVT dst, src
        .endif
        .endm

	; required for a symbol defined in another file
	.global	AES_Td0

	.text

	; These are equivalent.  Use the one you prefer.
	LDR_REPLACE r12, AES_Td0
	LDR_REPLACE r12, =AES_Td0

That macro is adapted from this post. I presume the array AES_Td0 is defined in a different file. The .global directive must be used in every file that defines or uses a global symbol.

The directives and macros supported by the TI ARM assembler are documented in the TI ARM assembly tools manual.

Thanks and regards,

-George

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Compiler/RM42L432: LDR pseudo instruction replacement