From: Jacob Lifshay Date: Tue, 10 Oct 2023 01:21:40 +0000 (-0700) Subject: merely indent function X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=3e3d4126f916dab94044ce8c5292c0e627bc8d18;p=openpower-isa.git merely indent function [skip ci] --- diff --git a/src/openpower/test/bigint/powmod.py b/src/openpower/test/bigint/powmod.py index 38ffeb45..91c0acfc 100644 --- a/src/openpower/test/bigint/powmod.py +++ b/src/openpower/test/bigint/powmod.py @@ -282,167 +282,167 @@ class DivModKnuthAlgorithmD: self.word_size = word_size -def python_divmod_knuth_algorithm_d(n, d, word_size=64, log_regex=False, - on_corner_case=lambda desc: None): - do_log = _DivModRegsRegexLogger(enabled=log_regex).log + def python_divmod_knuth_algorithm_d(n, d, word_size=64, log_regex=False, + on_corner_case=lambda desc: None): + do_log = _DivModRegsRegexLogger(enabled=log_regex).log + + # switch to names used by Knuth's algorithm D + u = list(n) # dividend + m = len(u) # length of dividend + v = list(d) # divisor + del d # less confusing to debug + n = len(v) # length of divisor + + assert m >= n, "the dividend's length must be >= the divisor's length" + assert word_size > 0 - # switch to names used by Knuth's algorithm D - u = list(n) # dividend - m = len(u) # length of dividend - v = list(d) # divisor - del d # less confusing to debug - n = len(v) # length of divisor - - assert m >= n, "the dividend's length must be >= the divisor's length" - assert word_size > 0 - - # allocate outputs/temporaries -- before any normalization so - # the outputs/temporaries can be fixed-length in the assembly version. - - # quotient length from original algorithm is m - n + 1, - # but that assumes v[-1] != 0 -- since we support smaller divisors the - # quotient must be larger. - q = [0] * m # quotient - r = [0] * n # remainder - vn = [0] * n # normalized divisor - un = [0] * (m + 1) # normalized dividend - product = [0] * (n + 1) - - # get non-zero length of dividend - while m > 0 and u[m - 1] == 0: - m -= 1 - - # get non-zero length of divisor - while n > 0 and v[n - 1] == 0: - n -= 1 - - if n == 0: - raise ZeroDivisionError - - if n == 1: - on_corner_case("single-word divisor") - # Knuth's algorithm D requires the divisor to have length >= 2 - # handle single-word divisors separately + # allocate outputs/temporaries -- before any normalization so + # the outputs/temporaries can be fixed-length in the assembly version. + + # quotient length from original algorithm is m - n + 1, + # but that assumes v[-1] != 0 -- since we support smaller divisors the + # quotient must be larger. + q = [0] * m # quotient + r = [0] * n # remainder + vn = [0] * n # normalized divisor + un = [0] * (m + 1) # normalized dividend + product = [0] * (n + 1) + + # get non-zero length of dividend + while m > 0 and u[m - 1] == 0: + m -= 1 + + # get non-zero length of divisor + while n > 0 and v[n - 1] == 0: + n -= 1 + + if n == 0: + raise ZeroDivisionError + + if n == 1: + on_corner_case("single-word divisor") + # Knuth's algorithm D requires the divisor to have length >= 2 + # handle single-word divisors separately + t = 0 + for i in reversed(range(m)): + # divmod2du + t <<= word_size + t += u[i] + q[i] = t // v[0] + t %= v[0] + r[0] = t + return q, r + + if m < n: + # dividend < divisor + for i in range(m): + r[i] = u[i] + return q, r + + # Knuth's algorithm D starts here: + + # Step D1: normalize + + # calculate amount to shift by -- count leading zeros + s = 0 + while (v[n - 1] << s) >> (word_size - 1) == 0: + s += 1 + + if s != 0: + on_corner_case("non-zero shift") + + # vn = v << s t = 0 - for i in reversed(range(m)): - # divmod2du - t <<= word_size - t += u[i] - q[i] = t // v[0] - t %= v[0] - r[0] = t - return q, r + for i in range(n): + # dsld + t |= v[i] << s + vn[i] = t % 2 ** word_size + t >>= word_size - if m < n: - # dividend < divisor + # un = u << s + t = 0 for i in range(m): - r[i] = u[i] - return q, r + # dsld + t |= u[i] << s + un[i] = t % 2 ** word_size + t >>= word_size + un[m] = t - # Knuth's algorithm D starts here: - - # Step D1: normalize - - # calculate amount to shift by -- count leading zeros - s = 0 - while (v[n - 1] << s) >> (word_size - 1) == 0: - s += 1 - - if s != 0: - on_corner_case("non-zero shift") - - # vn = v << s - t = 0 - for i in range(n): - # dsld - t |= v[i] << s - vn[i] = t % 2 ** word_size - t >>= word_size - - # un = u << s - t = 0 - for i in range(m): - # dsld - t |= u[i] << s - un[i] = t % 2 ** word_size - t >>= word_size - un[m] = t - - # Step D2 and Step D7: loop - for j in range(m - n, -1, -1): - # Step D3: calculate q̂ - - t = un[j + n] - t <<= word_size - t += un[j + n - 1] - if un[j + n] >= vn[n - 1]: - # division overflows word - on_corner_case("qhat overflows word") - qhat = 2 ** word_size - 1 - rhat = t - qhat * vn[n - 1] - else: - # divmod2du - qhat = t // vn[n - 1] - rhat = t % vn[n - 1] - - while rhat < 2 ** word_size: - if qhat * vn[n - 2] > (rhat << word_size) + un[j + n - 2]: - on_corner_case("qhat adjustment") - qhat -= 1 - rhat += vn[n - 1] + # Step D2 and Step D7: loop + for j in range(m - n, -1, -1): + # Step D3: calculate q̂ + + t = un[j + n] + t <<= word_size + t += un[j + n - 1] + if un[j + n] >= vn[n - 1]: + # division overflows word + on_corner_case("qhat overflows word") + qhat = 2 ** word_size - 1 + rhat = t - qhat * vn[n - 1] else: - break + # divmod2du + qhat = t // vn[n - 1] + rhat = t % vn[n - 1] + + while rhat < 2 ** word_size: + if qhat * vn[n - 2] > (rhat << word_size) + un[j + n - 2]: + on_corner_case("qhat adjustment") + qhat -= 1 + rhat += vn[n - 1] + else: + break - # Step D4: multiply and subtract + # Step D4: multiply and subtract - t = 0 - for i in range(n): - # maddedu - t += vn[i] * qhat - product[i] = t % 2 ** word_size - t >>= word_size - product[n] = t - - t = 1 - for i in range(n + 1): - # subfe - not_product = ~product[i] % 2 ** word_size - t += not_product + un[j + i] - un[j + i] = t % 2 ** word_size - t = int(t >= 2 ** word_size) - need_fixup = not t + t = 0 + for i in range(n): + # maddedu + t += vn[i] * qhat + product[i] = t % 2 ** word_size + t >>= word_size + product[n] = t + + t = 1 + for i in range(n + 1): + # subfe + not_product = ~product[i] % 2 ** word_size + t += not_product + un[j + i] + un[j + i] = t % 2 ** word_size + t = int(t >= 2 ** word_size) + need_fixup = not t - # Step D5: test remainder + # Step D5: test remainder - q[j] = qhat - if need_fixup: + q[j] = qhat + if need_fixup: - # Step D6: add back + # Step D6: add back - on_corner_case("add back") + on_corner_case("add back") - q[j] -= 1 + q[j] -= 1 - t = 0 - for i in range(n): - # adde - t += un[j + i] + vn[i] - un[j + i] = t % 2 ** word_size - t = int(t >= 2 ** word_size) - un[j + n] += t + t = 0 + for i in range(n): + # adde + t += un[j + i] + vn[i] + un[j + i] = t % 2 ** word_size + t = int(t >= 2 ** word_size) + un[j + n] += t - # Step D8: un-normalize + # Step D8: un-normalize - # r = un >> s - t = 0 - for i in reversed(range(n)): - # dsrd - t <<= word_size - t |= (un[i] << word_size) >> s - r[i] = t >> word_size - t %= 2 ** word_size + # r = un >> s + t = 0 + for i in reversed(range(n)): + # dsrd + t <<= word_size + t |= (un[i] << word_size) >> s + r[i] = t >> word_size + t %= 2 ** word_size - return q, r + return q, r POWMOD_256_ASM = (