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cxxrtl: Remove redundant divmod

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Merry 2023-12-09 14:07:54 +00:00 committed by Catherine
parent e6021b2b48
commit 99c8143ded
1 changed files with 3 additions and 89 deletions
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92
backends/cxxrtl/runtime/cxxrtl/cxxrtl.h
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@ -519,14 +519,6 @@ struct value : public expr_base<value<Bits>> {
return count;
}
size_t chunks_used() const {
for (size_t n = chunks; n > 0; n--) {
if (data[n - 1] != 0)
return n;
}
return 0;
}
template<bool Invert, bool CarryIn>
std::pair<value<Bits>, bool /*CarryOut*/> alu(const value<Bits> &other) const {
value<Bits> result;
@ -584,84 +576,6 @@ struct value : public expr_base<value<Bits>> {
result.data[result.chunks - 1] &= result.msb_mask;
return result;
}
// parallel to BigUnsigned::divideWithRemainder; quotient is stored in q,
// *this is left with the remainder. See that function for commentary describing
// how/why this works.
void divideWithRemainder(const value<Bits> &b, value<Bits> &q) {
assert(this != &q);
if (this == &b || &q == &b) {
value<Bits> tmpB(b);
divideWithRemainder(tmpB, q);
return;
}
q = value<Bits> {0u};
size_t blen = b.chunks_used();
if (blen == 0) {
return;
}
size_t len = chunks_used();
if (len < blen) {
return;
}
size_t i, j, k;
size_t i2;
chunk_t temp;
bool borrowIn, borrowOut;
size_t origLen = len;
len++;
chunk::type blk[len];
std::copy(data, data + origLen, blk);
blk[origLen] = 0;
chunk::type subtractBuf[len];
std::fill(subtractBuf, subtractBuf + len, 0);
size_t qlen = origLen - blen + 1;
i = qlen;
while (i > 0) {
i--;
i2 = chunk::bits;
while (i2 > 0) {
i2--;
for (j = 0, k = i, borrowIn = false; j <= blen; j++, k++) {
temp = blk[k] - getShiftedBlock(b, j, i2);
borrowOut = (temp > blk[k]);
if (borrowIn) {
borrowOut |= (temp == 0);
temp--;
}
subtractBuf[k] = temp;
borrowIn = borrowOut;
}
for (; k < origLen && borrowIn; k++) {
borrowIn = (blk[k] == 0);
subtractBuf[k] = blk[k] - 1;
}
if (!borrowIn) {
q.data[i] |= (chunk::type(1) << i2);
while (k > i) {
k--;
blk[k] = subtractBuf[k];
}
}
}
}
std::copy(blk, blk + origLen, data);
}
static chunk::type getShiftedBlock(const value<Bits> &num, size_t x, size_t y) {
chunk::type part1 = (x == 0 || y == 0) ? 0 : (num.data[x - 1] >> (chunk::bits - y));
chunk::type part2 = (x == num.chunks) ? 0 : (num.data[x] << y);
return part1 | part2;
}
};
// Expression template for a slice, usable as lvalue or rvalue, and composable with other expression templates here.
@ -849,9 +763,9 @@ std::ostream &operator<<(std::ostream &os, const value_formatted<Bits> &vf)
if (val.is_zero())
buf += '0';
while (!val.is_zero()) {
value<Bits> quotient;
val.divideWithRemainder(value<Bits>{10u}, quotient);
buf += '0' + val.template trunc<(Bits > 4 ? 4 : Bits)>().val().template get<uint8_t>();
value<Bits> quotient, remainder;
std::tie(quotient, remainder) = val.template divmod_uu<Bits>(value<Bits>{10u});
buf += '0' + remainder.template trunc<(Bits > 4 ? 4 : Bits)>().val().template get<uint8_t>();
val = quotient;
}
if (negative || vf.plus)