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// Copyright 2018 The Amber Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "src/vulkan/bit_copy.h"
#include <cassert>
#include <cstring>
namespace amber {
namespace vulkan {
// static
void BitCopy::ShiftBufferBits(uint8_t* buffer,
uint8_t length_bytes,
uint8_t shift_bits) {
if (shift_bits == 0)
return;
assert(shift_bits < 8);
uint8_t carry = 0;
for (uint32_t i = 0; i < length_bytes; ++i) {
uint8_t new_value = static_cast<uint8_t>(buffer[i] << shift_bits) | carry;
carry = buffer[i] >> (8 - shift_bits);
buffer[i] = new_value;
}
}
// static
void BitCopy::CopyValueToBuffer(uint8_t* dst,
const Value& src,
uint8_t bit_offset,
uint8_t bits) {
uint8_t data[9] = {};
if (src.IsInteger()) {
if (bits <= 8) {
uint8_t data_uint8 = src.AsUint8();
data[0] = data_uint8;
} else if (bits <= 16) {
uint16_t data_uint16 = src.AsUint16();
std::memcpy(data, &data_uint16, sizeof(uint16_t));
} else if (bits <= 32) {
uint32_t data_uint32 = src.AsUint32();
std::memcpy(data, &data_uint32, sizeof(uint32_t));
} else if (bits <= 64) {
uint64_t data_uint64 = src.AsUint64();
std::memcpy(data, &data_uint64, sizeof(uint64_t));
} else {
assert(false && "Invalid int bits for CopyBits");
}
} else {
if (bits == 64) {
double data_double = src.AsDouble();
std::memcpy(data, &data_double, sizeof(double));
} else {
float data_float = src.AsFloat();
uint16_t hex_float = 0;
switch (bits) {
case 32:
std::memcpy(data, &data_float, sizeof(float));
break;
case 16:
case 11:
case 10:
hex_float = FloatToHexFloat(data_float, bits);
std::memcpy(data, &hex_float, sizeof(uint16_t));
break;
default:
assert(false && "Invalid float bits for CopyBits");
break;
}
}
}
while (bit_offset > 7) {
++dst;
bit_offset -= 8;
}
ShiftBufferBits(data, ((bit_offset + bits - 1) / 8) + 1, bit_offset);
CopyBits(dst, data, bit_offset, bits);
}
// static
void BitCopy::CopyBits(uint8_t* dst,
const uint8_t* src,
uint8_t bit_offset,
uint8_t bits) {
while (bit_offset + bits > 0) {
uint8_t target_bits = bits;
if (bit_offset + target_bits > 8)
target_bits = 8 - bit_offset;
uint8_t bit_mask =
static_cast<uint8_t>(((1U << target_bits) - 1U) << bit_offset);
*dst = (*src & bit_mask) | (*dst & ~bit_mask);
bit_offset -= bit_offset;
bits -= target_bits;
++dst;
++src;
}
}
// static
uint16_t BitCopy::FloatExponent(const uint32_t hex_float) {
uint32_t exponent = ((hex_float >> 23U) & ((1U << 8U) - 1U)) - 127U + 15U;
const uint32_t half_exponent_mask = (1U << 5U) - 1U;
assert((exponent & ~half_exponent_mask) == 0U);
return static_cast<uint16_t>(exponent & half_exponent_mask);
}
// static
uint16_t BitCopy::FloatToHexFloat(float value, uint8_t bits) {
switch (bits) {
case 10:
return FloatToHexFloat10(value);
case 11:
return FloatToHexFloat11(value);
case 16:
return FloatToHexFloat16(value);
}
assert(false && "Invalid bits");
return 0;
}
// static
uint16_t BitCopy::FloatToHexFloat16(const float value) {
uint32_t hex;
memcpy(&hex, &value, sizeof(float));
return static_cast<uint16_t>(FloatSign(hex) << 15U) |
static_cast<uint16_t>(FloatExponent(hex) << 10U) | FloatMantissa(hex);
}
// static
uint16_t BitCopy::FloatToHexFloat11(const float value) {
uint32_t hex;
memcpy(&hex, &value, sizeof(float));
assert(FloatSign(hex) == 0);
return static_cast<uint16_t>(FloatExponent(hex) << 6U) |
static_cast<uint16_t>(FloatMantissa(hex) >> 4U);
}
// static
uint16_t BitCopy::FloatToHexFloat10(const float value) {
uint32_t hex;
memcpy(&hex, &value, sizeof(float));
assert(FloatSign(hex) == 0);
return static_cast<uint16_t>(FloatExponent(hex) << 5U) |
static_cast<uint16_t>(FloatMantissa(hex) >> 5U);
}
} // namespace vulkan
} // namespace amber
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