Skip to content

Commit

Permalink
3738: style improvement and comments
Browse files Browse the repository at this point in the history
  • Loading branch information
@jeanmon
jeanmon committed Jan 12, 2024
1 parent fab58b9 commit 267b1a1
Showing 1 changed file with 41 additions and 33 deletions.
74 changes: 41 additions & 33 deletions barretenberg/cpp/src/barretenberg/vm/avm_trace/AvmMini_alu_trace.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -53,8 +53,8 @@ FF AvmMiniAluTraceBuilder::add(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
c = a + b;
break;
case AvmMemoryTag::u8: {
uint8_t a_u8 = static_cast<uint8_t>(uint256_t(a).data[0]);
uint8_t b_u8 = static_cast<uint8_t>(uint256_t(b).data[0]);
auto a_u8 = static_cast<uint8_t>(uint32_t{ a });
auto b_u8 = static_cast<uint8_t>(uint32_t{ b });
uint8_t c_u8 = a_u8 + b_u8;
c = FF{ uint256_t{ c_u8 } };

Expand All @@ -67,8 +67,8 @@ FF AvmMiniAluTraceBuilder::add(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u16: {
uint16_t a_u16 = static_cast<uint16_t>(uint256_t(a).data[0]);
uint16_t b_u16 = static_cast<uint16_t>(uint256_t(b).data[0]);
auto a_u16 = static_cast<uint16_t>(uint32_t{ a });
auto b_u16 = static_cast<uint16_t>(uint32_t{ b });
uint16_t c_u16 = a_u16 + b_u16;
c = FF{ uint256_t{ c_u16 } };

Expand All @@ -81,8 +81,8 @@ FF AvmMiniAluTraceBuilder::add(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u32: {
uint32_t a_u32 = static_cast<uint32_t>(uint256_t(a).data[0]);
uint32_t b_u32 = static_cast<uint32_t>(uint256_t(b).data[0]);
uint32_t a_u32{ a };
uint32_t b_u32{ b };
uint32_t c_u32 = a_u32 + b_u32;
c = FF{ uint256_t{ c_u32 } };

Expand All @@ -96,8 +96,8 @@ FF AvmMiniAluTraceBuilder::add(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u64: {
uint64_t a_u64 = static_cast<uint64_t>(uint256_t(a).data[0]);
uint64_t b_u64 = static_cast<uint64_t>(uint256_t(b).data[0]);
uint64_t a_u64{ a };
uint64_t b_u64{ b };
uint64_t c_u64 = a_u64 + b_u64;
c = FF{ uint256_t{ c_u64 } };

Expand All @@ -114,8 +114,8 @@ FF AvmMiniAluTraceBuilder::add(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u128: {
auto a_u128 = uint128_t(a);
auto b_u128 = uint128_t(b);
uint128_t a_u128{ a };
uint128_t b_u128{ b };
uint128_t c_u128 = a_u128 + b_u128;
c = FF{ uint256_t::from_uint128(c_u128) };

Expand Down Expand Up @@ -178,8 +178,8 @@ FF AvmMiniAluTraceBuilder::sub(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
c = a - b;
break;
case AvmMemoryTag::u8: {
uint8_t a_u8 = static_cast<uint8_t>(uint256_t(a).data[0]);
uint8_t b_u8 = static_cast<uint8_t>(uint256_t(b).data[0]);
auto a_u8 = static_cast<uint8_t>(uint32_t{ a });
auto b_u8 = static_cast<uint8_t>(uint32_t{ b });
uint8_t c_u8 = a_u8 - b_u8;
c = FF{ uint256_t{ c_u8 } };

Expand All @@ -194,8 +194,8 @@ FF AvmMiniAluTraceBuilder::sub(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u16: {
uint16_t a_u16 = static_cast<uint16_t>(uint256_t(a).data[0]);
uint16_t b_u16 = static_cast<uint16_t>(uint256_t(b).data[0]);
auto a_u16 = static_cast<uint16_t>(uint32_t{ a });
auto b_u16 = static_cast<uint16_t>(uint32_t{ b });
uint16_t c_u16 = a_u16 - b_u16;
c = FF{ uint256_t{ c_u16 } };

Expand All @@ -210,8 +210,8 @@ FF AvmMiniAluTraceBuilder::sub(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u32: {
uint32_t a_u32 = static_cast<uint32_t>(uint256_t(a).data[0]);
uint32_t b_u32 = static_cast<uint32_t>(uint256_t(b).data[0]);
uint32_t a_u32{ a };
uint32_t b_u32{ b };
uint32_t c_u32 = a_u32 - b_u32;
c = FF{ uint256_t{ c_u32 } };

Expand All @@ -227,8 +227,8 @@ FF AvmMiniAluTraceBuilder::sub(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u64: {
uint64_t a_u64 = static_cast<uint64_t>(uint256_t(a).data[0]);
uint64_t b_u64 = static_cast<uint64_t>(uint256_t(b).data[0]);
uint64_t a_u64{ a };
uint64_t b_u64{ b };
uint64_t c_u64 = a_u64 - b_u64;
c = FF{ uint256_t{ c_u64 } };

Expand All @@ -247,8 +247,8 @@ FF AvmMiniAluTraceBuilder::sub(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u128: {
auto a_u128 = uint128_t(a);
auto b_u128 = uint128_t(b);
uint128_t a_u128{ a };
uint128_t b_u128{ b };
uint128_t c_u128 = a_u128 - b_u128;
c = FF{ uint256_t::from_uint128(c_u128) };

Expand Down Expand Up @@ -315,8 +315,8 @@ FF AvmMiniAluTraceBuilder::mul(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
c = a * b;
break;
case AvmMemoryTag::u8: {
uint16_t a_u16 = static_cast<uint16_t>(uint256_t(a).data[0]);
uint16_t b_u16 = static_cast<uint16_t>(uint256_t(b).data[0]);
auto a_u16 = static_cast<uint16_t>(uint32_t{ a });
auto b_u16 = static_cast<uint16_t>(uint32_t{ b });
uint16_t c_u16 = a_u16 * b_u16; // Multiplication over the integers (not mod. 2^8)

// Decompose c_u16 = r0 + 2^8 * r1 with r0, r1 8-bit registers
Expand All @@ -327,8 +327,8 @@ FF AvmMiniAluTraceBuilder::mul(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u16: {
uint32_t a_u32 = static_cast<uint32_t>(uint256_t(a).data[0]);
uint32_t b_u32 = static_cast<uint32_t>(uint256_t(b).data[0]);
uint32_t a_u32{ a };
uint32_t b_u32{ b };
uint32_t c_u32 = a_u32 * b_u32; // Multiplication over the integers (not mod. 2^16)

// Decompose c_u32 = r0 + 2^16 * r1 with r0, r1 16-bit registers
Expand All @@ -339,8 +339,8 @@ FF AvmMiniAluTraceBuilder::mul(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u32: {
uint64_t a_u64 = static_cast<uint64_t>(uint256_t(a).data[0]);
uint64_t b_u64 = static_cast<uint64_t>(uint256_t(b).data[0]);
uint64_t a_u64{ a };
uint64_t b_u64{ b };
uint64_t c_u64 = a_u64 * b_u64; // Multiplication over the integers (not mod. 2^32)

// Decompose c_u64 = r0 + 2^16 * r1 + 2^32 * r2 + 2^48 * r3 with r0, r1, r2, r3 16-bit registers
Expand All @@ -355,8 +355,8 @@ FF AvmMiniAluTraceBuilder::mul(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u64: {
uint128_t a_u128 = static_cast<uint128_t>(uint256_t(a).data[0]);
uint128_t b_u128 = static_cast<uint128_t>(uint256_t(b).data[0]);
uint128_t a_u128{ a };
uint128_t b_u128{ b };
uint128_t c_u128 = a_u128 * b_u128; // Multiplication over the integers (not mod. 2^64)

// Decompose c_u128 = r0 + 2^16 * r1 + .. + 2^112 r7 with r0, r1 ... r7 16-bit registers
Expand All @@ -371,12 +371,12 @@ FF AvmMiniAluTraceBuilder::mul(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
break;
}
case AvmMemoryTag::u128: {
auto a_u256 = uint256_t(a);
auto b_u256 = uint256_t(b);
uint256_t a_u256{ a };
uint256_t b_u256{ a };
uint256_t c_u256 = a_u256 * b_u256; // Multiplication over the integers (not mod. 2^128)

auto a_u128 = static_cast<uint128_t>(a_u256);
auto b_u128 = static_cast<uint128_t>(b_u256);
uint128_t a_u128{ a_u256 };
uint128_t b_u128{ b_u256 };

uint128_t c_u128 = a_u128 * b_u128;

Expand All @@ -393,9 +393,17 @@ FF AvmMiniAluTraceBuilder::mul(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
b_trunc_128 >>= 16;
}

// Represent a, b with 64-bit limbs: a = a_l + 2^64 * a_h, b = b_l + 2^64 * b_h,
// c_high := 2^128 * a_h * b_h
uint256_t c_high = ((a_u256 >> 64) * (b_u256 >> 64)) << 128;

// From PIL relation in alu_chip.pil, we need to determine the bit CF and 64-bit value R' in
// a * b_l + a_l * b_h * 2^64 = (CF * 2^65 + R') * 2^128 + c
// LHS is c_u256 - c_high

// CF bit
carry = ((c_u256 - c_high) >> 193) > 0;
// R' value
uint64_t alu_u64_r0 = static_cast<uint64_t>(((c_u256 - c_high) >> 128) & uint256_t(UINT64_MAX));

c = FF{ uint256_t::from_uint128(c_u128) };
Expand All @@ -422,6 +430,7 @@ FF AvmMiniAluTraceBuilder::mul(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
return FF{ 0 };
}

// Following code executed for: ff, u8, u16, u32, u64 (u128 returned handled specifically)
alu_trace.push_back(AvmMiniAluTraceBuilder::AluTraceEntry{
.alu_clk = clk,
.alu_op_mul = true,
Expand All @@ -430,7 +439,6 @@ FF AvmMiniAluTraceBuilder::mul(FF const& a, FF const& b, AvmMemoryTag in_tag, ui
.alu_u16_tag = in_tag == AvmMemoryTag::u16,
.alu_u32_tag = in_tag == AvmMemoryTag::u32,
.alu_u64_tag = in_tag == AvmMemoryTag::u64,
.alu_u128_tag = in_tag == AvmMemoryTag::u128,
.alu_ia = a,
.alu_ib = b,
.alu_ic = c,
Expand Down

0 comments on commit 267b1a1

Please sign in to comment.