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cleanup compressors
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@desmonddak
desmonddak committed Aug 9, 2024
1 parent 3e29ad1 commit 2a29ceb
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Showing 6 changed files with 190 additions and 94 deletions.
139 changes: 62 additions & 77 deletions lib/src/arithmetic/addend_compressor.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,6 @@ import 'package:rohd/rohd.dart';
import 'package:rohd_hcl/src/arithmetic/multiplier_lib.dart';
import 'package:rohd_hcl/src/utils.dart';

// TODO(desmonddak): Logic and LogicValue majority() functions

/// Base class for column compressor function
abstract class AddendCompressor extends Module {
/// Input bits to compress
Expand Down Expand Up @@ -78,7 +76,7 @@ class CompressTerm implements Comparable<CompressTerm> {
late final CompressTermType type;

/// The inputs that drove this Term
late List<CompressTerm> inputs = <CompressTerm>[];
late final List<CompressTerm> inputs;

/// The row of the terminal
final int row;
Expand All @@ -87,7 +85,7 @@ class CompressTerm implements Comparable<CompressTerm> {
final int col;

/// The Logic wire of the term
final logic = Logic();
final Logic logic;

/// Estimated delay of the output of this CompessTerm
late double delay;
Expand All @@ -99,32 +97,18 @@ class CompressTerm implements Comparable<CompressTerm> {
static const carryDelay = 0.75;

/// CompressTerm constructor
CompressTerm(this.type, this.row, this.col) : delay = 0.0;

/// Create a sum Term
factory CompressTerm.sumTerm(List<CompressTerm> args, int row, int col) {
final term = CompressTerm(CompressTermType.sum, row, col);
// ignore: cascade_invocations
term.inputs = args;
for (final i in term.inputs) {
if (i.delay + sumDelay > term.delay) {
term.delay = i.delay + sumDelay;
}
}
return term;
}

/// Create a carry Term
factory CompressTerm.carryTerm(List<CompressTerm> args, int row, int col) {
final term = CompressTerm(CompressTermType.carry, row, col);
// ignore: cascade_invocations
term.inputs = args;
for (final i in term.inputs) {
if (i.delay + carryDelay > term.delay) {
term.delay = i.delay + carryDelay;
CompressTerm(this.type, this.logic, this.inputs, this.row, this.col) {
delay = 0.0;
final deltaDelay = switch (type) {
CompressTermType.carry => carryDelay,
CompressTermType.sum => sumDelay,
CompressTermType.pp => 0.0
};
for (final i in inputs) {
if (i.delay + deltaDelay > delay) {
delay = i.delay + deltaDelay;
}
}
return term;
}
@override
int compareTo(Object other) {
Expand All @@ -134,6 +118,41 @@ class CompressTerm implements Comparable<CompressTerm> {
return delay > other.delay ? 1 : (delay < other.delay ? -1 : 0);
}

/// Evaluate the logic value of a given CompressTerm.
LogicValue evaluate() {
late LogicValue value;
switch (type) {
case CompressTermType.pp:
value = logic.value;
case CompressTermType.sum:
// xor the eval of the terms
final termValues = [for (final term in inputs) term.evaluate()];
final sum = termValues.swizzle().xor();
value = sum;
case CompressTermType.carry:
final termValues = [for (final term in inputs) term.evaluate()];
final termValuesInt = [
for (var i = 0; i < termValues.length; i++) termValues[i].toInt()
];

final count = (termValuesInt.isNotEmpty)
? termValuesInt.reduce((c, term) => c + term)
: 0;
final majority =
(count > termValues.length ~/ 2 ? LogicValue.one : LogicValue.zero);
// Alternative method:
// final x = Logic(width: termValues.length);
// x.put(termValues.swizzle());
// final newCount = Count(x).index.value.toInt();
// stdout.write('count=$count newCount=$newCount\n');
// if (newCount != count) {
// throw RohdHclException('count=$count newCount=$newCount');
// }
value = majority;
}
return value;
}

@override
String toString() {
final str = StringBuffer();
Expand Down Expand Up @@ -167,50 +186,13 @@ class ColumnCompressor {
for (var row = 0; row < pp.rows; row++) {
for (var col = 0; col < pp.partialProducts[row].length; col++) {
final trueColumn = pp.rowShift[row] + col;
final term = CompressTerm(CompressTermType.pp, row, trueColumn);
term.logic <= pp.partialProducts[row][col];
final term = CompressTerm(CompressTermType.pp,
pp.partialProducts[row][col], [], row, trueColumn);
columns[trueColumn].add(term);
}
}
}

// TODO(desmonddak): This cannot run without real logic values due to toInt()
// which forces the user to assign values to the inputs first
// We need a way to build the CompressionTerm without actual values
// e.g., there needs to be a way to do the reductions with 'X' values
/// Evaluate the logic value of a given CompressTerm
LogicValue evaluateTerm(CompressTerm term) {
switch (term.type) {
case CompressTermType.pp:
return term.logic.value;
case CompressTermType.sum:
// xor the eval of the terms
final termValues = [for (term in term.inputs) evaluateTerm(term)];
final sum = termValues.swizzle().xor();
return sum;
case CompressTermType.carry:
final termValues = [for (term in term.inputs) evaluateTerm(term)];
final termValuesInt = [
for (var i = 0; i < termValues.length; i++) termValues[i].toInt()
];

final count = (termValuesInt.isNotEmpty)
? termValuesInt.reduce((c, term) => c + term)
: 0;
final majority =
(count > termValues.length ~/ 2 ? LogicValue.one : LogicValue.zero);
// Alternative method:
// final x = Logic(width: termValues.length);
// x.put(termValues.swizzle());
// final newCount = Count(x).index.value.toInt();
// stdout.write('count=$count newCount=$newCount\n');
// if (newCount 1= count) {
// throw RohdHclException('count=$count newCount=$newCount');
// }
return majority;
}
}

/// Return the longest column length
int longestColumn() =>
columns.reduce((a, b) => a.length > b.length ? a : b).length;
Expand All @@ -234,8 +216,8 @@ class ColumnCompressor {

/// Evaluate the (un)compressed partial product array
/// logic=true will read the logic gate outputs at each level
/// print=true will print out the array
BigInt evaluate({bool print = false, bool logic = false}) {
/// printOut=true will print out the array
BigInt evaluate({bool printOut = false, bool logic = false}) {
final ts = StringBuffer();
final rows = longestColumn();
final width = pp.maxWidth();
Expand All @@ -247,19 +229,19 @@ class ColumnCompressor {
final colList = columns[col].toList();
if (row < colList.length) {
final value =
logic ? colList[row].logic.value : evaluateTerm(colList[row]);
logic ? colList[row].logic.value : (colList[row].evaluate());
rowBits.add(value);
if (print) {
if (printOut) {
ts.write('\t${value.bitString}');
}
} else if (print) {
} else if (printOut) {
ts.write('\t');
}
}
rowBits.addAll(List.filled(pp.rowShift[row], LogicValue.zero));
final val = rowBits.swizzle().zeroExtend(width).toBigInt();
accum += val;
if (print) {
if (printOut) {
ts.write('\t${rowBits.swizzle().zeroExtend(width).bitString} ($val)');
if (row == rows - 1) {
ts.write(' Total=${accum.toSigned(width)}\n');
Expand All @@ -269,6 +251,9 @@ class ColumnCompressor {
}
}
}
if (printOut) {
print(ts);
}
return accum.toSigned(width);
}

Expand Down Expand Up @@ -308,15 +293,15 @@ class ColumnCompressor {
compressor =
Compressor2([for (final i in inputs) i.logic].swizzle());
}
final t = CompressTerm.sumTerm(inputs, 0, col);
t.logic <= compressor.sum;
final t = CompressTerm(
CompressTermType.sum, compressor.sum, inputs, 0, col);
terms.add(t);
columns[col].add(t);
if (col < columns.length - 1) {
final t = CompressTerm.carryTerm(inputs, 0, col);
final t = CompressTerm(
CompressTermType.carry, compressor.carry, inputs, 0, col);
columns[col + 1].add(t);
terms.add(t);
t.logic <= compressor.carry;
}
}
}
Expand Down
10 changes: 3 additions & 7 deletions lib/src/arithmetic/multiplier.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -84,14 +84,10 @@ class CompressionTreeMultiplier extends Multiplier {
Logic()
], (a, b) => Logic()).runtimeType}') {
final product = addOutput('product', width: a.width + b.width);

final pp =
PartialProductGenerator(a, b, RadixEncoder(radix), signed: signed);
// ignore: cascade_invocations
pp.signExtendCompact();
final compressor = ColumnCompressor(pp);
// ignore: cascade_invocations
compressor.compress();
PartialProductGenerator(a, b, RadixEncoder(radix), signed: signed)
..signExtendCompact();
final compressor = ColumnCompressor(pp)..compress();
final adder = ParallelPrefixAdder(
compressor.extractRow(0), compressor.extractRow(1), ppTree);
product <= adder.out.slice(a.width + b.width - 1, 0);
Expand Down
9 changes: 9 additions & 0 deletions lib/src/arithmetic/partial_product_generator.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,15 @@ class PartialProductGenerator {
encoder = MultiplierEncoder(multiplier, radixEncoder, signed: signed);
selector =
MultiplicandSelector(radixEncoder.radix, multiplicand, signed: signed);

if (multiplicand.width < selector.shift) {
throw RohdHclException('multiplicand width must be greater than '
'${selector.shift}');
}
if (multiplier.width < (selector.shift + (signed ? 1 : 0))) {
throw RohdHclException('multiplier width must be greater than '
'${selector.shift + (signed ? 1 : 0)}');
}
_build();
}

Expand Down
47 changes: 45 additions & 2 deletions test/arithmetic/addend_compressor_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -80,8 +80,8 @@ void main() {
stdout.write('\n');

for (final signed in [false, true]) {
for (var radix = 4; radix < 32; radix *= 2) {
final encoder = RadixEncoder(2);
for (var radix = 4; radix < 4; radix *= 2) {
final encoder = RadixEncoder(radix);
// stdout.write('encoding with radix=$radix\n');
final shift = log2Ceil(encoder.radix);
for (var width = shift + 1; width < 2 * shift + 1; width++) {
Expand All @@ -103,4 +103,47 @@ void main() {
}
}
});
test('single compressor evaluate mac', () async {
const widthX = 6;
const widthY = 9;
final a = Logic(name: 'a', width: widthX);
final b = Logic(name: 'b', width: widthY);

const av = 4;
const bv = 14;
for (final signed in [true, false]) {
final bA = signed
? BigInt.from(av).toSigned(widthX)
: BigInt.from(av).toUnsigned(widthX);
final bB = signed
? BigInt.from(bv).toSigned(widthY)
: BigInt.from(bv).toUnsigned(widthY);

// Set these so that printing inside module build will have Logic values
a.put(bA);
b.put(bB);
const radix = 4;
final encoder = RadixEncoder(radix);
final pp = PartialProductGenerator(a, b, encoder, signed: signed)
..signExtendCompactRect();
// Turn on printing by using widthX == 6 (we are fooling the dead code
// checking linter here)
const output = widthX == 7;
if (output) {
print(pp);
}
expect(pp.evaluate(), equals(BigInt.from(av * bv)));
final compressor = ColumnCompressor(pp);
if (output) {
print('eval: ${compressor.evaluate(printOut: output)}');
}
expect(compressor.evaluate(), equals(BigInt.from(av * bv)));

compressor.compress();
if (output) {
print('eval: ${compressor.evaluate(printOut: true)}');
}
expect(compressor.evaluate(), equals(BigInt.from(av * bv)));
}
});
}
3 changes: 1 addition & 2 deletions test/arithmetic/adder_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -125,8 +125,7 @@ void testExhaustiveSignMagnitude(int n, Adder Function(Logic a, Logic b) fn) {
bigger = bI;
smaller = bJ;
} else {
bigger = bJ;
smaller = bI;
continue;
}
final biggerSign = bigger.abs() != bigger ? 1 : 0;
final smallerSign = smaller.abs() != smaller ? 1 : 0;
Expand Down
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