| //===- AVR.cpp ------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // AVR is a Harvard-architecture 8-bit micrcontroller designed for small |
| // baremetal programs. All AVR-family processors have 32 8-bit registers. |
| // The tiniest AVR has 32 byte RAM and 1 KiB program memory, and the largest |
| // one supports up to 2^24 data address space and 2^22 code address space. |
| // |
| // Since it is a baremetal programming, there's usually no loader to load |
| // ELF files on AVRs. You are expected to link your program against address |
| // 0 and pull out a .text section from the result using objcopy, so that you |
| // can write the linked code to on-chip flush memory. You can do that with |
| // the following commands: |
| // |
| // ld.lld -Ttext=0 -o foo foo.o |
| // objcopy -O binary --only-section=.text foo output.bin |
| // |
| // Note that the current AVR support is very preliminary so you can't |
| // link any useful program yet, though. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "InputFiles.h" |
| #include "Symbols.h" |
| #include "Target.h" |
| #include "lld/Common/ErrorHandler.h" |
| #include "llvm/Object/ELF.h" |
| #include "llvm/Support/Endian.h" |
| |
| using namespace llvm; |
| using namespace llvm::object; |
| using namespace llvm::support::endian; |
| using namespace llvm::ELF; |
| using namespace lld; |
| using namespace lld::elf; |
| |
| namespace { |
| class AVR final : public TargetInfo { |
| public: |
| AVR(); |
| RelExpr getRelExpr(RelType type, const Symbol &s, |
| const uint8_t *loc) const override; |
| void relocate(uint8_t *loc, const Relocation &rel, |
| uint64_t val) const override; |
| }; |
| } // namespace |
| |
| AVR::AVR() { noneRel = R_AVR_NONE; } |
| |
| RelExpr AVR::getRelExpr(RelType type, const Symbol &s, |
| const uint8_t *loc) const { |
| return R_ABS; |
| } |
| |
| void AVR::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const { |
| switch (rel.type) { |
| case R_AVR_CALL: { |
| uint16_t hi = val >> 17; |
| uint16_t lo = val >> 1; |
| write16le(loc, read16le(loc) | ((hi >> 1) << 4) | (hi & 1)); |
| write16le(loc + 2, lo); |
| break; |
| } |
| default: |
| error(getErrorLocation(loc) + "unrecognized relocation " + |
| toString(rel.type)); |
| } |
| } |
| |
| TargetInfo *elf::getAVRTargetInfo() { |
| static AVR target; |
| return ⌖ |
| } |