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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
77 lines
2.5 KiB
C++
77 lines
2.5 KiB
C++
//===- AVR.cpp ------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// AVR is a Harvard-architecture 8-bit micrcontroller designed for small
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// baremetal programs. All AVR-family processors have 32 8-bit registers.
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// The tiniest AVR has 32 byte RAM and 1 KiB program memory, and the largest
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// one supports up to 2^24 data address space and 2^22 code address space.
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//
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// Since it is a baremetal programming, there's usually no loader to load
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// ELF files on AVRs. You are expected to link your program against address
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// 0 and pull out a .text section from the result using objcopy, so that you
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// can write the linked code to on-chip flush memory. You can do that with
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// the following commands:
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//
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// ld.lld -Ttext=0 -o foo foo.o
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// objcopy -O binary --only-section=.text foo output.bin
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//
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// Note that the current AVR support is very preliminary so you can't
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// link any useful program yet, though.
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//
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//===----------------------------------------------------------------------===//
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#include "InputFiles.h"
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#include "Symbols.h"
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#include "Target.h"
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#include "lld/Common/ErrorHandler.h"
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#include "llvm/Object/ELF.h"
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#include "llvm/Support/Endian.h"
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using namespace llvm;
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using namespace llvm::object;
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using namespace llvm::support::endian;
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using namespace llvm::ELF;
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using namespace lld;
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using namespace lld::elf;
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namespace {
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class AVR final : public TargetInfo {
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public:
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AVR();
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RelExpr getRelExpr(RelType Type, const Symbol &S,
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const uint8_t *Loc) const override;
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void relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const override;
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};
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} // namespace
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AVR::AVR() { NoneRel = R_AVR_NONE; }
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RelExpr AVR::getRelExpr(RelType Type, const Symbol &S,
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const uint8_t *Loc) const {
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return R_ABS;
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}
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void AVR::relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const {
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switch (Type) {
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case R_AVR_CALL: {
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uint16_t Hi = Val >> 17;
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uint16_t Lo = Val >> 1;
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write16le(Loc, read16le(Loc) | ((Hi >> 1) << 4) | (Hi & 1));
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write16le(Loc + 2, Lo);
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break;
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}
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default:
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error(getErrorLocation(Loc) + "unrecognized reloc " + toString(Type));
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}
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}
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TargetInfo *elf::getAVRTargetInfo() {
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static AVR Target;
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return &Target;
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}
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