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// This file is part of AsmJit project <https://asmjit.com>
//
// See asmjit.h or LICENSE.md for license and copyright information
// SPDX-License-Identifier: Zlib
#include "../core/api-build_p.h"
#include "../core/codeholder.h"
#include "../core/codewriter_p.h"
ASMJIT_BEGIN_NAMESPACE
bool CodeWriterUtils::encodeOffset32(uint32_t* dst, int64_t offset64, const OffsetFormat& format) noexcept {
uint32_t bitCount = format.immBitCount();
uint32_t bitShift = format.immBitShift();
uint32_t discardLsb = format.immDiscardLsb();
// Invalid offset (should not happen).
if (!bitCount || bitCount > format.valueSize() * 8u)
return false;
uint32_t value;
// First handle all unsigned offset types.
if (format.type() == OffsetType::kUnsignedOffset) {
if (discardLsb) {
ASMJIT_ASSERT(discardLsb <= 32);
if ((offset64 & Support::lsbMask<uint32_t>(discardLsb)) != 0)
return false;
offset64 = int64_t(uint64_t(offset64) >> discardLsb);
}
value = uint32_t(offset64 & Support::lsbMask<uint32_t>(bitCount));
if (value != offset64)
return false;
}
else {
// The rest of OffsetType options are all signed.
if (discardLsb) {
ASMJIT_ASSERT(discardLsb <= 32);
if ((offset64 & Support::lsbMask<uint32_t>(discardLsb)) != 0)
return false;
offset64 >>= discardLsb;
}
if (!Support::isInt32(offset64))
return false;
value = uint32_t(int32_t(offset64));
if (!Support::isEncodableOffset32(int32_t(value), bitCount))
return false;
}
switch (format.type()) {
case OffsetType::kSignedOffset:
case OffsetType::kUnsignedOffset: {
*dst = (value & Support::lsbMask<uint32_t>(bitCount)) << bitShift;
return true;
}
case OffsetType::kAArch64_ADR:
case OffsetType::kAArch64_ADRP: {
// Sanity checks.
if (format.valueSize() != 4 || bitCount != 21 || bitShift != 5)
return false;
uint32_t immLo = value & 0x3u;
uint32_t immHi = (value >> 2) & Support::lsbMask<uint32_t>(19);
*dst = (immLo << 29) | (immHi << 5);
return true;
}
default:
return false;
}
}
bool CodeWriterUtils::encodeOffset64(uint64_t* dst, int64_t offset64, const OffsetFormat& format) noexcept {
uint32_t bitCount = format.immBitCount();
uint32_t discardLsb = format.immDiscardLsb();
if (!bitCount || bitCount > format.valueSize() * 8u)
return false;
uint64_t value;
// First handle all unsigned offset types.
if (format.type() == OffsetType::kUnsignedOffset) {
if (discardLsb) {
ASMJIT_ASSERT(discardLsb <= 32);
if ((offset64 & Support::lsbMask<uint32_t>(discardLsb)) != 0)
return false;
offset64 = int64_t(uint64_t(offset64) >> discardLsb);
}
value = uint64_t(offset64) & Support::lsbMask<uint64_t>(bitCount);
if (value != uint64_t(offset64))
return false;
}
else {
// The rest of OffsetType options are all signed.
if (discardLsb) {
ASMJIT_ASSERT(discardLsb <= 32);
if ((offset64 & Support::lsbMask<uint32_t>(discardLsb)) != 0)
return false;
offset64 >>= discardLsb;
}
if (!Support::isEncodableOffset64(offset64, bitCount))
return false;
value = uint64_t(offset64);
}
switch (format.type()) {
case OffsetType::kSignedOffset:
case OffsetType::kUnsignedOffset: {
*dst = (value & Support::lsbMask<uint64_t>(bitCount)) << format.immBitShift();
return true;
}
default:
return false;
}
}
bool CodeWriterUtils::writeOffset(void* dst, int64_t offset64, const OffsetFormat& format) noexcept {
// Offset the destination by ValueOffset so the `dst` points to the
// patched word instead of the beginning of the patched region.
dst = static_cast<char*>(dst) + format.valueOffset();
switch (format.valueSize()) {
case 1: {
uint32_t mask;
if (!encodeOffset32(&mask, offset64, format))
return false;
Support::writeU8(dst, uint8_t(Support::readU8(dst) | mask));
return true;
}
case 2: {
uint32_t mask;
if (!encodeOffset32(&mask, offset64, format))
return false;
Support::writeU16uLE(dst, uint16_t(Support::readU16uLE(dst) | mask));
return true;
}
case 4: {
uint32_t mask;
if (!encodeOffset32(&mask, offset64, format)) {
return false;
}
Support::writeU32uLE(dst, Support::readU32uLE(dst) | mask);
return true;
}
case 8: {
uint64_t mask;
if (!encodeOffset64(&mask, offset64, format))
return false;
Support::writeU64uLE(dst, Support::readU64uLE(dst) | mask);
return true;
}
default:
return false;
}
}
ASMJIT_END_NAMESPACE
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