forked from OSchip/llvm-project
77 lines
2.5 KiB
C++
77 lines
2.5 KiB
C++
//===- 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 relocateOne(uint8_t *Loc, RelType Type, 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::relocateOne(uint8_t *Loc, RelType 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 relocation " + toString(Type));
|
|
}
|
|
}
|
|
|
|
TargetInfo *elf::getAVRTargetInfo() {
|
|
static AVR Target;
|
|
return &Target;
|
|
}
|