diff options
Diffstat (limited to 'ELF/Arch/AVR.cpp')
-rw-r--r-- | ELF/Arch/AVR.cpp | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/ELF/Arch/AVR.cpp b/ELF/Arch/AVR.cpp new file mode 100644 index 000000000000..86343a6faa16 --- /dev/null +++ b/ELF/Arch/AVR.cpp @@ -0,0 +1,78 @@ +//===- AVR.cpp ------------------------------------------------------------===// +// +// The LLVM Linker +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// 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 "Error.h" +#include "InputFiles.h" +#include "Memory.h" +#include "Symbols.h" +#include "Target.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: + RelExpr getRelExpr(uint32_t Type, const SymbolBody &S, + const uint8_t *Loc) const override; + void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const override; +}; +} // namespace + +RelExpr AVR::getRelExpr(uint32_t Type, const SymbolBody &S, + const uint8_t *Loc) const { + switch (Type) { + case R_AVR_CALL: + return R_ABS; + default: + error(toString(S.File) + ": unknown relocation type: " + toString(Type)); + return R_HINT; + } +} + +void AVR::relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const { + switch (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 reloc " + toString(Type)); + } +} + +TargetInfo *elf::createAVRTargetInfo() { return make<AVR>(); } |