def generate_scheme(self):
""" main scheme generation """
Log.report(Log.Info, "width parameter is {}".format(self.width))
int_size = 3
frac_size = self.width - int_size
input_precision = fixed_point(int_size, frac_size)
output_precision = fixed_point(int_size, frac_size)
# declaring main input variable
var_x = self.implementation.add_input_signal("x", input_precision)
var_y = self.implementation.add_input_signal("y", input_precision)
var_x.set_attributes(debug = debug_fixed)
var_y.set_attributes(debug = debug_fixed)
sub = var_x - var_y
c = Constant(0)
self.implementation.start_new_stage()
#pre_result = Select(
# c > sub,
# c,
# sub
#)
pre_result = Max(0, sub)
self.implementation.start_new_stage()
result = Conversion(pre_result + var_x, precision=output_precision)
self.implementation.add_output_signal("vr_out", result)
return [self.implementation]
def subnormalize(x_list, factor, precision=None, fma=True):
""" x_list is a multi-component number with components ordered from the
most to the least siginificant.
x_list[0] must be the rounded evaluation of (x_list[0] + x_list[1] + ...)
@return the field of x as a floating-point number assuming
the exponent of the result is exponent(x) + factor
and managing field subnormalization if required """
x_hi = x_list[0]
int_precision = precision.get_integer_format()
ex = ExponentExtraction(x_hi, precision=int_precision)
scaled_ex = ex + factor
# difference betwen x's real exponent and the minimal exponent
# for a floating of format precision
CI0 = Constant(0, precision=int_precision)
CI1 = Constant(1, precision=int_precision)
delta = Max(Min(precision.get_emin() - scaled_ex, CI0),
Constant(precision.get_field_size(), precision=int_precision))
casted_int_x = TypeCast(x_hi, precision=int_precision)
# compute a constant to be added to a casted floating-point to perform
# rounding. This constant shall be equivalent to a half-ulp
round_cst = BitLogicLeftShift(CI1, delta - 1, precision=int_precision)
pre_rounded_value = TypeCast(casted_int_x + round_cst, precision=precision)
sticky_shift = precision.get_bit_size() - (delta - 1)
sticky = BitLogicLeftShift(casted_int_x,
sticky_shift,
precision=int_precision)
low_sticky_sign = CI0
if len(x_list) > 1:
for x_op in x_list[1:]:
sticky = BitLogicOr(sticky, x_op)
low_sticky_sign = BitLogicOr(
BitLogicXor(CopySign(x_hi), CopySign(x_op)), low_sticky_sign)
# does the low sticky (x_list[1:]) differs in signedness from x_hi ?
parity_bit = BitLogicAnd(casted_int_x,
BitLogicLeftShift(1,
delta,
precision=int_precision),
precision=int_precision)
inc_select = LogicalAnd(Equal(sticky, CI0), Equal(parity_bit, CI0))
rounded_value = Select(inc_select,
x,
pre_rounded_value,
precision=precision)
# cleaning trailing-bits
return TypeCast(BitLogicRightShift(BitLogicLeftShift(
TypeCast(rounded_value, precision=int_precision),
delta,
precision=int_precision),
delta,
precision=int_precision),
precision=precision)
def subnormalize_multi(x_list, factor, precision=None, fma=True):
""" x_list is a multi-component number with components ordered from the
most to the least siginificant.
x_list[0] must be the rounded evaluation of (x_list[0] + x_list[1] + ...)
@return the field of x as a floating-point number assuming
the exponent of the result is exponent(x) + factor
and managing field subnormalization if required """
x_hi = x_list[0]
int_precision = precision.get_integer_format()
ex = ExponentExtraction(x_hi, precision=int_precision)
scaled_ex = Addition(ex, factor, precision=int_precision)
CI0 = Constant(0, precision=int_precision)
CI1 = Constant(1, precision=int_precision)
# difference betwen x's real exponent and the minimal exponent
# for a floating of format precision
delta = Max(Min(Subtraction(Constant(precision.get_emin_normal(),
precision=int_precision),
scaled_ex,
precision=int_precision),
CI0,
precision=int_precision),
Constant(precision.get_field_size(), precision=int_precision),
precision=int_precision)
round_factor_exp = Addition(delta, ex, precision=int_precision)
round_factor = ExponentInsertion(round_factor_exp, precision=precision)
# to force a rounding as if x_hi was of precision p - delta
# we use round_factor as follows:
# o(o(round_factor + x_hi) - round_factor)
if len(x_list) == 2:
rounded_x_hi = Subtraction(Add112(round_factor,
x_list[0],
x_list[1],
precision=precision)[0],
round_factor,
precision=precision)
elif len(x_list) == 3:
rounded_x_hi = Subtraction(Add113(round_factor,
x_list[0],
x_list[1],
x_list[2],
precision=precision)[0],
round_factor,
precision=precision)
else:
Log.report(Log.Error,
"len of x_list: {} is not supported in subnormalize_multi",
len(x_list))
raise NotImplementedError
return [rounded_x_hi] + [
Constant(0, precision=precision) for i in range(len(x_list) - 1)
]
def generate_scalar_scheme(self, vx):
output_precision = self.precision
input_precision = vx.get_precision()
bias = -output_precision.get_bias()
bound_exp = Max(Min(
vx, output_precision.get_emax(), precision=input_precision),
output_precision.get_emin_normal(),
precision=input_precision) + bias
scheme = Return(ExponentInsertion(bound_exp,
specifier=ExponentInsertion.NoOffset,
precision=self.precision),
tag="result",
debug=debug_multi)
return scheme
def generate_scheme(self):
""" main scheme generation """
Log.report(Log.Info, "width parameter is {}".format(self.width))
int_size = 3
frac_size = self.width - int_size
input_precision = fixed_point(int_size, frac_size)
output_precision = fixed_point(int_size, frac_size)
# declaring main input variable
var_x = self.implementation.add_input_signal("x", input_precision)
var_y = self.implementation.add_input_signal("y", input_precision)
var_x.set_attributes(debug=debug_fixed)
var_y.set_attributes(debug=debug_fixed)
test = (var_x > 1)
test.set_attributes(tag="test", debug=debug_std)
sub = var_x - var_y
c = Constant(0)
pre_result_select = Select(c > sub,
Select(c < var_y,
sub,
Select(LogicalAnd(
c > var_x,
c < var_y,
tag="last_lev_cond"),
var_x,
c,
tag="last_lev_sel"),
tag="pre_select"),
var_y,
tag="pre_result_select")
pre_result = Max(0, var_x - var_y, tag="pre_result")
result = Conversion(Addition(pre_result, pre_result_select, tag="add"),
precision=output_precision)
self.implementation.add_output_signal("vr_out", result)
return [self.implementation]
def piecewise_approximation(function,
variable,
precision,
bound_low=-1.0,
bound_high=1.0,
num_intervals=16,
max_degree=2,
error_threshold=S2**-24,
odd=False,
even=False):
""" Generate a piecewise approximation
:param function: function to be approximated
:type function: SollyaObject
:param variable: input variable
:type variable: Variable
:param precision: variable's format
:type precision: ML_Format
:param bound_low: lower bound for the approximation interval
:param bound_high: upper bound for the approximation interval
:param num_intervals: number of sub-interval / sub-division of the main interval
:param max_degree: maximum degree for an approximation on any sub-interval
:param error_threshold: error bound for an approximation on any sub-interval
:return: pair (scheme, error) where scheme is a graph node for an
approximation scheme of function evaluated at variable, and error
is the maximum approximation error encountered
:rtype tuple(ML_Operation, SollyaObject): """
degree_generator = piecewise_approximation_degree_generator(
function,
bound_low,
bound_high,
num_intervals=num_intervals,
error_threshold=error_threshold,
)
degree_list = list(degree_generator)
# if max_degree is None then we determine it locally
if max_degree is None:
max_degree = max(degree_list)
# table to store coefficients of the approximation on each segment
coeff_table = ML_NewTable(
dimensions=[num_intervals, max_degree + 1],
storage_precision=precision,
tag="coeff_table",
const=True # by default all approximation coeff table are const
)
error_function = lambda p, f, ai, mod, t: sollya.dirtyinfnorm(p - f, ai)
max_approx_error = 0.0
interval_size = (bound_high - bound_low) / num_intervals
for i in range(num_intervals):
subint_low = bound_low + i * interval_size
subint_high = bound_low + (i + 1) * interval_size
local_function = function(sollya.x + subint_low)
local_interval = Interval(-interval_size, interval_size)
local_degree = degree_list[i]
if local_degree > max_degree:
Log.report(
Log.Warning,
"local_degree {} exceeds max_degree bound ({}) in piecewise_approximation",
local_degree, max_degree)
# as max_degree defines the size of the table we can use
# it as the degree for each sub-interval polynomial
# as there is nothing to gain (yet) by using a smaller polynomial
degree = max_degree # min(max_degree, local_degree)
if function(subint_low) == 0.0:
# if the lower bound is a zero to the function, we
# need to force value=0 for the constant coefficient
# and extend the approximation interval
local_poly_degree_list = list(
range(1 if even else 0, degree + 1, 2 if odd or even else 1))
poly_object, approx_error = Polynomial.build_from_approximation_with_error(
function(sollya.x) / sollya.x,
local_poly_degree_list,
[precision] * len(local_poly_degree_list),
Interval(-subint_high * 0.95, subint_high),
sollya.absolute,
error_function=error_function)
# multiply by sollya.x
poly_object = poly_object.sub_poly(offset=-1)
else:
try:
poly_object, approx_error = Polynomial.build_from_approximation_with_error(
local_function,
degree, [precision] * (degree + 1),
local_interval,
sollya.absolute,
error_function=error_function)
except SollyaError as err:
# try to see if function is constant on the interval (possible
# failure cause for fpminmax)
cst_value = precision.round_sollya_object(
function(subint_low), sollya.RN)
accuracy = error_threshold
diff_with_cst_range = sollya.supnorm(cst_value, local_function,
local_interval,
sollya.absolute, accuracy)
diff_with_cst = sup(abs(diff_with_cst_range))
if diff_with_cst < error_threshold:
Log.report(Log.Info, "constant polynomial detected")
poly_object = Polynomial([function(subint_low)] +
[0] * degree)
approx_error = diff_with_cst
else:
Log.report(
Log.error,
"degree: {} for index {}, diff_with_cst={} (vs error_threshold={}) ",
degree,
i,
diff_with_cst,
error_threshold,
error=err)
for ci in range(max_degree + 1):
if ci in poly_object.coeff_map:
coeff_table[i][ci] = poly_object.coeff_map[ci]
else:
coeff_table[i][ci] = 0.0
if approx_error > error_threshold:
Log.report(
Log.Warning,
"piecewise_approximation on index {} exceeds error threshold: {} > {}",
i, approx_error, error_threshold)
max_approx_error = max(max_approx_error, abs(approx_error))
# computing offset
diff = Subtraction(variable,
Constant(bound_low, precision=precision),
tag="diff",
debug=debug_multi,
precision=precision)
int_prec = precision.get_integer_format()
# delta = bound_high - bound_low
delta_ratio = Constant(num_intervals / (bound_high - bound_low),
precision=precision)
# computing table index
# index = nearestint(diff / delta * <num_intervals>)
index = Max(0,
Min(
NearestInteger(
Multiplication(diff, delta_ratio, precision=precision),
precision=int_prec,
), num_intervals - 1),
tag="index",
debug=debug_multi,
precision=int_prec)
poly_var = Subtraction(diff,
Multiplication(
Conversion(index, precision=precision),
Constant(interval_size, precision=precision)),
precision=precision,
tag="poly_var",
debug=debug_multi)
# generating indexed polynomial
coeffs = [(ci, TableLoad(coeff_table, index, ci))
for ci in range(max_degree + 1)][::-1]
poly_scheme = PolynomialSchemeEvaluator.generate_horner_scheme2(
coeffs, poly_var, precision, {}, precision)
return poly_scheme, max_approx_error
def generate_scheme(self):
# We wish to compute vx / vy
vx = self.implementation.add_input_variable(
"x", self.precision, interval=self.input_intervals[0])
vy = self.implementation.add_input_variable(
"y", self.precision, interval=self.input_intervals[1])
# maximum exponent magnitude (to avoid overflow/ underflow during
# intermediary computations
int_prec = self.precision.get_integer_format()
max_exp_mag = Constant(self.precision.get_emax() - 1,
precision=int_prec)
exact_ex = ExponentExtraction(vx,
tag="exact_ex",
precision=int_prec,
debug=debug_multi)
exact_ey = ExponentExtraction(vy,
tag="exact_ey",
precision=int_prec,
debug=debug_multi)
ex = Max(Min(exact_ex, max_exp_mag, precision=int_prec),
-max_exp_mag,
tag="ex",
precision=int_prec)
ey = Max(Min(exact_ey, max_exp_mag, precision=int_prec),
-max_exp_mag,
tag="ey",
precision=int_prec)
Attributes.set_default_rounding_mode(ML_RoundToNearest)
Attributes.set_default_silent(True)
# computing the inverse square root
init_approx = None
scaling_factor_x = ExponentInsertion(-ex,
tag="sfx_ei",
precision=self.precision,
debug=debug_multi)
scaling_factor_y = ExponentInsertion(-ey,
tag="sfy_ei",
precision=self.precision,
debug=debug_multi)
def test_interval_out_of_bound_risk(x_range, y_range):
""" Try to determine from x and y's interval if there is a risk
of underflow or overflow """
div_range = abs(x_range / y_range)
underflow_risk = sollya.inf(div_range) < S2**(
self.precision.get_emin_normal() + 2)
overflow_risk = sollya.sup(div_range) > S2**(
self.precision.get_emax() - 2)
return underflow_risk or overflow_risk
out_of_bound_risk = (self.input_intervals[0] is None
or self.input_intervals[1] is None
) or test_interval_out_of_bound_risk(
self.input_intervals[0],
self.input_intervals[1])
Log.report(Log.Debug,
"out_of_bound_risk: {}".format(out_of_bound_risk))
# scaled version of vx and vy, to avoid overflow and underflow
if out_of_bound_risk:
scaled_vx = vx * scaling_factor_x
scaled_vy = vy * scaling_factor_y
scaled_interval = MetaIntervalList(
[MetaInterval(Interval(-2, -1)),
MetaInterval(Interval(1, 2))])
scaled_vx.set_attributes(tag="scaled_vx",
debug=debug_multi,
interval=scaled_interval)
scaled_vy.set_attributes(tag="scaled_vy",
debug=debug_multi,
interval=scaled_interval)
seed_interval = 1 / scaled_interval
print("seed_interval=1/{}={}".format(scaled_interval,
seed_interval))
else:
scaled_vx = vx
scaled_vy = vy
seed_interval = 1 / scaled_vy.get_interval()
# We need a first approximation to 1 / scaled_vy
dummy_seed = ReciprocalSeed(EmptyOperand(precision=self.precision),
precision=self.precision)
if self.processor.is_supported_operation(dummy_seed, self.language):
init_approx = ReciprocalSeed(scaled_vy,
precision=self.precision,
tag="init_approx",
debug=debug_multi)
else:
# generate tabulated version of seed
raise NotImplementedError
current_approx_std = init_approx
# correctly-rounded inverse computation
num_iteration = self.num_iter
Attributes.unset_default_rounding_mode()
Attributes.unset_default_silent()
# check if inputs are zeros
x_zero = Test(vx,
specifier=Test.IsZero,
likely=False,
precision=ML_Bool)
y_zero = Test(vy,
specifier=Test.IsZero,
likely=False,
precision=ML_Bool)
comp_sign = Test(vx,
vy,
specifier=Test.CompSign,
tag="comp_sign",
debug=debug_multi)
# check if divisor is NaN
y_nan = Test(vy, specifier=Test.IsNaN, likely=False, precision=ML_Bool)
# check if inputs are signaling NaNs
x_snan = Test(vx,
specifier=Test.IsSignalingNaN,
likely=False,
precision=ML_Bool)
y_snan = Test(vy,
specifier=Test.IsSignalingNaN,
likely=False,
precision=ML_Bool)
# check if inputs are infinities
x_inf = Test(vx,
specifier=Test.IsInfty,
likely=False,
tag="x_inf",
precision=ML_Bool)
y_inf = Test(vy,
specifier=Test.IsInfty,
likely=False,
tag="y_inf",
debug=debug_multi,
precision=ML_Bool)
scheme = None
gappa_vx, gappa_vy = None, None
# initial reciprocal approximation of 1.0 / scaled_vy
inv_iteration_list, recp_approx = compute_reduced_reciprocal(
init_approx, scaled_vy, self.num_iter)
recp_approx.set_attributes(tag="recp_approx", debug=debug_multi)
# approximation of scaled_vx / scaled_vy
yerr_last, reduced_div_approx, div_iteration_list = compute_reduced_division(
scaled_vx, scaled_vy, recp_approx)
eval_error_range, div_eval_error_range = self.solve_eval_error(
init_approx, recp_approx, reduced_div_approx, scaled_vx, scaled_vy,
inv_iteration_list, div_iteration_list, S2**-7, seed_interval)
eval_error = sup(abs(eval_error_range))
recp_interval = 1 / scaled_vy.get_interval() + eval_error_range
recp_approx.set_interval(recp_interval)
div_interval = scaled_vx.get_interval() / scaled_vy.get_interval(
) + div_eval_error_range
reduced_div_approx.set_interval(div_interval)
reduced_div_approx.set_tag("reduced_div_approx")
if out_of_bound_risk:
unscaled_result = scaling_div_result(reduced_div_approx, ex,
scaling_factor_y,
self.precision)
subnormal_result = subnormalize_result(recp_approx,
reduced_div_approx, ex, ey,
yerr_last, self.precision)
else:
unscaled_result = reduced_div_approx
subnormal_result = reduced_div_approx
x_inf_or_nan = Test(vx, specifier=Test.IsInfOrNaN, likely=False)
y_inf_or_nan = Test(vy,
specifier=Test.IsInfOrNaN,
likely=False,
tag="y_inf_or_nan",
debug=debug_multi)
# generate IEEE exception raising only of libm-compliant
# mode is enabled
enable_raise = self.libm_compliant
# managing special cases
# x inf and y inf
pre_scheme = ConditionBlock(
x_inf_or_nan,
ConditionBlock(
x_inf,
ConditionBlock(
y_inf_or_nan,
Statement(
# signaling NaNs raise invalid operation flags
ConditionBlock(y_snan, Raise(ML_FPE_Invalid))
if enable_raise else Statement(),
Return(FP_QNaN(self.precision)),
),
ConditionBlock(comp_sign,
Return(FP_MinusInfty(self.precision)),
Return(FP_PlusInfty(self.precision)))),
Statement(
ConditionBlock(x_snan, Raise(ML_FPE_Invalid))
if enable_raise else Statement(),
Return(FP_QNaN(self.precision)))),
ConditionBlock(
x_zero,
ConditionBlock(
LogicalOr(y_zero, y_nan, precision=ML_Bool),
Statement(
ConditionBlock(y_snan, Raise(ML_FPE_Invalid))
if enable_raise else Statement(),
Return(FP_QNaN(self.precision))), Return(vx)),
ConditionBlock(
y_inf_or_nan,
ConditionBlock(
y_inf,
Return(
Select(comp_sign, FP_MinusZero(self.precision),
FP_PlusZero(self.precision))),
Statement(
ConditionBlock(y_snan, Raise(ML_FPE_Invalid))
if enable_raise else Statement(),
Return(FP_QNaN(self.precision)))),
ConditionBlock(
y_zero,
Statement(
Raise(ML_FPE_DivideByZero)
if enable_raise else Statement(),
ConditionBlock(
comp_sign,
Return(FP_MinusInfty(self.precision)),
Return(FP_PlusInfty(self.precision)))),
# managing numerical value result cases
Statement(
recp_approx,
reduced_div_approx,
ConditionBlock(
Test(unscaled_result,
specifier=Test.IsSubnormal,
likely=False),
# result is subnormal
Statement(
# inexact flag should have been raised when computing yerr_last
# ConditionBlock(
# Comparison(
# yerr_last, 0,
# specifier=Comparison.NotEqual, likely=True),
# Statement(Raise(ML_FPE_Inexact, ML_FPE_Underflow))
#),
Return(subnormal_result), ),
# result is normal
Statement(
# inexact flag should have been raised when computing yerr_last
#ConditionBlock(
# Comparison(
# yerr_last, 0,
# specifier=Comparison.NotEqual, likely=True),
# Raise(ML_FPE_Inexact)
#),
Return(unscaled_result))),
)))))
# managing rounding mode save and restore
# to ensure intermediary computations are performed in round-to-nearest
# clearing exception before final computation
#rnd_mode = GetRndMode()
#scheme = Statement(
# rnd_mode,
# SetRndMode(ML_RoundToNearest),
# yerr_last,
# SetRndMode(rnd_mode),
# unscaled_result,
# ClearException(),
# pre_scheme
#)
scheme = pre_scheme
return scheme
def generate_scheme(self):
""" main scheme generation """
int_size = 3
frac_size = self.width - int_size
input_precision = fixed_point(int_size, frac_size)
output_precision = fixed_point(int_size, frac_size)
expected_interval = {}
# declaring main input variable
var_x = self.implementation.add_input_signal("x", input_precision)
x_interval = Interval(-10.3,10.7)
var_x.set_interval(x_interval)
expected_interval[var_x] = x_interval
var_y = self.implementation.add_input_signal("y", input_precision)
y_interval = Interval(-17.9,17.2)
var_y.set_interval(y_interval)
expected_interval[var_y] = y_interval
var_z = self.implementation.add_input_signal("z", input_precision)
z_interval = Interval(-7.3,7.7)
var_z.set_interval(z_interval)
expected_interval[var_z] = z_interval
cst = Constant(42.5, tag = "cst")
expected_interval[cst] = Interval(42.5)
conv_ceil = Ceil(var_x, tag = "ceil")
expected_interval[conv_ceil] = sollya.ceil(x_interval)
conv_floor = Floor(var_y, tag = "floor")
expected_interval[conv_floor] = sollya.floor(y_interval)
mult = var_z * var_x
mult.set_tag("mult")
mult_interval = z_interval * x_interval
expected_interval[mult] = mult_interval
large_add = (var_x + var_y) - mult
large_add.set_attributes(tag = "large_add")
large_add_interval = (x_interval + y_interval) - mult_interval
expected_interval[large_add] = large_add_interval
var_x_lzc = CountLeadingZeros(var_x, tag="var_x_lzc")
expected_interval[var_x_lzc] = Interval(0, input_precision.get_bit_size())
reduced_result = Max(0, Min(large_add, 13))
reduced_result.set_tag("reduced_result")
reduced_result_interval = interval_max(
Interval(0),
interval_min(
large_add_interval,
Interval(13)
)
)
expected_interval[reduced_result] = reduced_result_interval
select_result = Select(
var_x > var_y,
reduced_result,
var_z,
tag = "select_result"
)
select_interval = interval_union(reduced_result_interval, z_interval)
expected_interval[select_result] = select_interval
# floating-point operation on mantissa and exponents
fp_x_range = Interval(-0.01, 100)
unbound_fp_var = Variable("fp_x", precision=ML_Binary32, interval=fp_x_range)
mant_fp_x = MantissaExtraction(unbound_fp_var, tag="mant_fp_x", precision=ML_Binary32)
exp_fp_x = ExponentExtraction(unbound_fp_var, tag="exp_fp_x", precision=ML_Int32)
ins_exp_fp_x = ExponentInsertion(exp_fp_x, tag="ins_exp_fp_x", precision=ML_Binary32)
expected_interval[unbound_fp_var] = fp_x_range
expected_interval[exp_fp_x] = Interval(
sollya.floor(sollya.log2(sollya.inf(abs(fp_x_range)))),
sollya.floor(sollya.log2(sollya.sup(abs(fp_x_range))))
)
expected_interval[mant_fp_x] = Interval(1, 2)
expected_interval[ins_exp_fp_x] = Interval(
S2**sollya.inf(expected_interval[exp_fp_x]),
S2**sollya.sup(expected_interval[exp_fp_x])
)
# checking interval evaluation
for var in [var_x_lzc, exp_fp_x, unbound_fp_var, mant_fp_x, ins_exp_fp_x, cst, var_x, var_y, mult, large_add, reduced_result, select_result, conv_ceil, conv_floor]:
interval = evaluate_range(var)
expected = expected_interval[var]
print("{}: {}".format(var.get_tag(), interval))
print(" vs expected {}".format(expected))
assert not interval is None
assert interval == expected
return [self.implementation]
def generate_scheme(self):
""" main scheme generation """
int_size = 3
frac_size = self.width - int_size
input_precision = fixed_point(int_size, frac_size)
output_precision = fixed_point(int_size, frac_size)
expected_interval = {}
# declaring main input variable
var_x = self.implementation.add_input_signal("x", input_precision)
x_interval = Interval(-10.3, 10.7)
var_x.set_interval(x_interval)
expected_interval[var_x] = x_interval
var_y = self.implementation.add_input_signal("y", input_precision)
y_interval = Interval(-17.9, 17.2)
var_y.set_interval(y_interval)
expected_interval[var_y] = y_interval
var_z = self.implementation.add_input_signal("z", input_precision)
z_interval = Interval(-7.3, 7.7)
var_z.set_interval(z_interval)
expected_interval[var_z] = z_interval
cst = Constant(42.5, tag="cst")
expected_interval[cst] = Interval(42.5)
conv_ceil = Ceil(var_x, tag="ceil")
expected_interval[conv_ceil] = sollya.ceil(x_interval)
conv_floor = Floor(var_y, tag="floor")
expected_interval[conv_floor] = sollya.floor(y_interval)
mult = var_z * var_x
mult.set_tag("mult")
mult_interval = z_interval * x_interval
expected_interval[mult] = mult_interval
large_add = (var_x + var_y) - mult
large_add.set_attributes(tag="large_add")
large_add_interval = (x_interval + y_interval) - mult_interval
expected_interval[large_add] = large_add_interval
reduced_result = Max(0, Min(large_add, 13))
reduced_result.set_tag("reduced_result")
reduced_result_interval = interval_max(
Interval(0), interval_min(large_add_interval, Interval(13)))
expected_interval[reduced_result] = reduced_result_interval
select_result = Select(var_x > var_y,
reduced_result,
var_z,
tag="select_result")
select_interval = interval_union(reduced_result_interval, z_interval)
expected_interval[select_result] = select_interval
# checking interval evaluation
for var in [
cst, var_x, var_y, mult, large_add, reduced_result,
select_result, conv_ceil, conv_floor
]:
interval = evaluate_range(var)
expected = expected_interval[var]
print("{}: {} vs expected {}".format(var.get_tag(), interval,
expected))
assert not interval is None
assert interval == expected
return [self.implementation]
def piecewise_approximation(function,
variable,
precision,
bound_low=-1.0,
bound_high=1.0,
num_intervals=16,
max_degree=2,
error_threshold=sollya.S2**-24):
""" To be documented """
# table to store coefficients of the approximation on each segment
coeff_table = ML_NewTable(dimensions=[num_intervals, max_degree + 1],
storage_precision=precision,
tag="coeff_table")
error_function = lambda p, f, ai, mod, t: sollya.dirtyinfnorm(p - f, ai)
max_approx_error = 0.0
interval_size = (bound_high - bound_low) / num_intervals
for i in range(num_intervals):
subint_low = bound_low + i * interval_size
subint_high = bound_low + (i + 1) * interval_size
#local_function = function(sollya.x)
#local_interval = Interval(subint_low, subint_high)
local_function = function(sollya.x + subint_low)
local_interval = Interval(-interval_size, interval_size)
local_degree = sollya.guessdegree(local_function, local_interval,
error_threshold)
degree = min(max_degree, local_degree)
if function(subint_low) == 0.0:
# if the lower bound is a zero to the function, we
# need to force value=0 for the constant coefficient
# and extend the approximation interval
degree_list = range(1, degree + 1)
poly_object, approx_error = Polynomial.build_from_approximation_with_error(
function(sollya.x),
degree_list, [precision] * len(degree_list),
Interval(-subint_high, subint_high),
sollya.absolute,
error_function=error_function)
else:
try:
poly_object, approx_error = Polynomial.build_from_approximation_with_error(
local_function,
degree, [precision] * (degree + 1),
local_interval,
sollya.absolute,
error_function=error_function)
except SollyaError as err:
print("degree: {}".format(degree))
raise err
for ci in range(degree + 1):
if ci in poly_object.coeff_map:
coeff_table[i][ci] = poly_object.coeff_map[ci]
else:
coeff_table[i][ci] = 0.0
max_approx_error = max(max_approx_error, abs(approx_error))
# computing offset
diff = Subtraction(variable,
Constant(bound_low, precision=precision),
tag="diff",
precision=precision)
# delta = bound_high - bound_low
delta_ratio = Constant(num_intervals / (bound_high - bound_low),
precision=precision)
# computing table index
# index = nearestint(diff / delta * <num_intervals>)
index = Max(0,
Min(
NearestInteger(Multiplication(diff,
delta_ratio,
precision=precision),
precision=ML_Int32), num_intervals - 1),
tag="index",
debug=True,
precision=ML_Int32)
poly_var = Subtraction(diff,
Multiplication(
Conversion(index, precision=precision),
Constant(interval_size, precision=precision)),
precision=precision,
tag="poly_var",
debug=True)
# generating indexed polynomial
coeffs = [(ci, TableLoad(coeff_table, index, ci))
for ci in range(degree + 1)][::-1]
poly_scheme = PolynomialSchemeEvaluator.generate_horner_scheme2(
coeffs, poly_var, precision, {}, precision)
return poly_scheme, max_approx_error
def generate_scheme(self):
""" main scheme generation """
int_size = 3
frac_size = self.width - int_size
input_precision = hdl_precision_parser("FU%d.%d" %
(int_size, frac_size))
output_precision = hdl_precision_parser("FS%d.%d" %
(int_size, frac_size))
# declaring main input variable
var_x = self.implementation.add_input_signal("x", input_precision)
var_y = self.implementation.add_input_signal("y", input_precision)
var_z = self.implementation.add_input_signal("z", input_precision)
abstract_formulae = var_x + var_y * var_z + 7
round_bit = BitSelection(
abstract_formulae,
FixedPointPosition(abstract_formulae,
0,
align=FixedPointPosition.FromPointToLSB),
)
msb_bit = BitSelection(
abstract_formulae,
FixedPointPosition(abstract_formulae,
0,
align=FixedPointPosition.FromMSBToLSB))
lsb_bit = BitSelection(
abstract_formulae,
FixedPointPosition(abstract_formulae,
0,
align=FixedPointPosition.FromLSBToLSB))
# testing parameterized fixed-point format
dynamic_format = lazy_fixed_point(
FixedPointPosition(abstract_formulae,
0,
tag="lazy_up",
align=FixedPointPosition.FromPointToMSB) -
Max(
0,
FixedPointPosition(abstract_formulae,
2,
align=FixedPointPosition.FromLSBToLSB) - 2),
FixedPointPosition(
abstract_formulae, 0, align=FixedPointPosition.FromPointToLSB)
+ Min(
FixedPointPosition(abstract_formulae,
2,
align=FixedPointPosition.FromPointToLSB) -
0,
FixedPointPosition(
abstract_formulae,
2,
align=FixedPointPosition.FromPointToLSB,
) - 0),
)
result = Constant(3, precision=dynamic_format)
self.implementation.add_output_signal("round", round_bit)
self.implementation.add_output_signal("msb", msb_bit)
self.implementation.add_output_signal("lsb", lsb_bit)
self.implementation.add_output_signal("result", result)
return [self.implementation]