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allow rationals to be raised to integer powers, trap divide and mod b…
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…y zero
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@billhails
billhails committed Apr 5, 2024
1 parent b5cbf20 commit c77f3ce
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Showing 2 changed files with 85 additions and 16 deletions.
4 changes: 3 additions & 1 deletion fn/rational.fn
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Original file line number Diff line number Diff line change
Expand Up @@ -5,10 +5,12 @@ print(#( "4 + 2 / 3 + 4", 4 + 2 / 3 + 4 ));
print(#( "4 + 2 / -3 + 4", 4 + 2 / -3 + 4 ));
print(#( "2 / 3 + 4 / 5", 2 / 3 + 4 / 5 ));
print(#( "(2 / 3) * (4 / 5)", (2 / 3) * (4 / 5) ));
print(#( "(2 / 3) / (4 / 5)", (2 / 3) / (4 / 5) ));
print(#( "(6 / 5)", (6 / 5) ));
print(#( "(2 / 3) / (6 / 5)", (2 / 3) / (6 / 5) ));
print(#( "(2 / 3) % (4 / 5)", (2 / 3) % (4 / 5) ));
print(#( "1914882942 ** 10", 1914882942 ** 10 ));
print(#( "1/3 % 8", 1/3 % 8 ));
print(#( "-9 % 8", -9 % 8 ));
print(#( "(1/2) ** 2", (1/2) ** 2 ));
print(#( "(1914882942 ** 5 / 5) % (2 / 3)", (1914882942 ** 5 / 5) % (2 / 3) ))

97 changes: 82 additions & 15 deletions src/arithmetic.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,11 @@ static Value One = {
.val = VALUE_VAL_STDINT(1)
};

static Value Zero = {
.type = VALUE_TYPE_STDINT,
.val = VALUE_VAL_STDINT(0)
};

#ifdef DEBUG_ARITHMETIC
static void ppNumber(Value number) {
switch (number.type) {
Expand Down Expand Up @@ -98,6 +103,12 @@ static Value intValue(int i) {
# define ASSERT_STDINT(x)
#endif

static int littleCmp(Value left, Value right) {
ASSERT_STDINT(left);
ASSERT_STDINT(right);
return left.val.stdint < right.val.stdint ? -1 : left.val.stdint == right.val.stdint ? 0 : 1;
}

static Value littleAdd(Value left, Value right) {
ASSERT_STDINT(left);
ASSERT_STDINT(right);
Expand All @@ -119,6 +130,9 @@ static Value littleSub(Value left, Value right) {
static Value littleDivide(Value left, Value right) {
ASSERT_STDINT(left);
ASSERT_STDINT(right);
if (littleCmp(right, Zero) == 0) {
cant_happen("attempted div zero");
}
return intValue(left.val.stdint / right.val.stdint);
}

Expand All @@ -131,6 +145,9 @@ static Value littlePower(Value left, Value right) {
static Value littleModulo(Value left, Value right) {
ASSERT_STDINT(left);
ASSERT_STDINT(right);
if (littleCmp(right, Zero) == 0) {
cant_happen("attempted mod zero");
}
return intValue(left.val.stdint % right.val.stdint);
}

Expand All @@ -153,12 +170,6 @@ static Value littleGcd(Value left, Value right) {
return intValue(gcd(left.val.stdint, right.val.stdint));
}

static int littleCmp(Value left, Value right) {
ASSERT_STDINT(left);
ASSERT_STDINT(right);
return left.val.stdint < right.val.stdint ? -1 : left.val.stdint == right.val.stdint ? 0 : 1;
}

static void littleNeg(Value v) {
ASSERT_STDINT(v);
v.val.stdint = -v.val.stdint;
Expand All @@ -179,6 +190,14 @@ static bool littleIsNeg(Value v) {
# define ASSERT_BIGINT(x)
#endif

static int bigCmp(Value left, Value right) {
ENTER(bigCmp);
ASSERT_BIGINT(left);
ASSERT_BIGINT(right);
LEAVE(bigCmp);
return cmpBigInt(left.val.bigint, right.val.bigint);
}

static Value bigIntValue(BigInt *i) {
Value val;
val.type = VALUE_TYPE_BIGINT;
Expand Down Expand Up @@ -232,6 +251,9 @@ static Value bigDivide(Value left, Value right) {
IFDEBUG(ppNumber(right));
ASSERT_BIGINT(left);
ASSERT_BIGINT(right);
if (bigCmp(right, Zero) == 0) {
cant_happen("attempted div zero");
}
BigInt *result = divBigInt(left.val.bigint, right.val.bigint);
int save = PROTECT(result);
Value res = bigIntValue(result);
Expand All @@ -258,6 +280,9 @@ static Value bigModulo(Value left, Value right) {
ENTER(bigModulo);
ASSERT_BIGINT(left);
ASSERT_BIGINT(right);
if (bigCmp(right, Zero) == 0) {
cant_happen("attempted mod zero");
}
BigInt *result = modBigInt(left.val.bigint, right.val.bigint);
int save = PROTECT(result);
Value res = bigIntValue(result);
Expand All @@ -278,14 +303,6 @@ static Value bigGcd(Value left, Value right) {
return res;
}

static int bigCmp(Value left, Value right) {
ENTER(bigCmp);
ASSERT_BIGINT(left);
ASSERT_BIGINT(right);
LEAVE(bigCmp);
return cmpBigInt(left.val.bigint, right.val.bigint);
}

static void bigNeg(Value v) {
ASSERT_BIGINT(v);
negateBigInt(v.val.bigint);
Expand Down Expand Up @@ -499,6 +516,52 @@ static Value ratModulo(Value left, Value right) {
return res;
}

static Value _ratPower(Value left, Value right) {
ENTER(_ratPower);
ASSERT_RATIONAL(left);
Value numerator = left.val.vec->values[NUMERATOR];
Value denominator = left.val.vec->values[DENOMINATOR];
numerator = int_power(numerator, right);
int save = protectValue(numerator);
denominator = int_power(denominator, right);
protectValue(denominator);
Value res = ratSimplify(numerator, denominator);
protectValue(res);
LEAVE(_ratPower);
IFDEBUG(ppNumber(res));
UNPROTECT(save);
return res;
}

static Value ratPower(Value left, Value right) {
ENTER(ratPower);
LEAVE(ratPower);
IFDEBUG(ppNumber(left));
IFDEBUG(ppNumber(right));
Value res;
int save = protectValue(left);
protectValue(right);
if (left.type == VALUE_TYPE_RATIONAL) {
if (right.type == VALUE_TYPE_RATIONAL) {
cant_happen("raising numbers to a rational power not supported yet");
} else {
// only left rational
res = _ratPower(left, right);
protectValue(res);
}
} else if (right.type == VALUE_TYPE_RATIONAL) {
cant_happen("raising numbers to a rational power not supported yet");
} else {
// neither rational
res = int_power(left, right);
protectValue(res);
}
LEAVE(ratPower);
IFDEBUG(ppNumber(res));
UNPROTECT(save);
return res;
}

void init_arithmetic() {
if (bigint_flag) {
int_add = bigAdd;
Expand All @@ -511,6 +574,9 @@ void init_arithmetic() {
int_cmp = bigCmp;
int_neg = bigNeg;
int_isneg = bigIsNeg;
BigInt *zero = bigIntFromInt(0);
Zero.type = VALUE_TYPE_BIGINT;
Zero.val = VALUE_VAL_BIGINT(zero);
BigInt *one = bigIntFromInt(1);
One.type = VALUE_TYPE_BIGINT;
One.val = VALUE_VAL_BIGINT(one);
Expand All @@ -532,7 +598,7 @@ void init_arithmetic() {
sub = ratSub;
mul = ratMul;
divide = ratDivide;
power = int_power;
power = ratPower;
modulo = ratModulo;
} else {
add = int_add;
Expand All @@ -545,5 +611,6 @@ void init_arithmetic() {
}

void markArithmetic() {
markValue(Zero);
markValue(One);
}

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