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WIP: IEEE754

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This commit is contained in:
7400
2023-11-17 08:30:23 -08:00
parent e9fd472ec1
commit 8b871940eb
2 changed files with 41 additions and 12 deletions
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31
test/TestIEEE754.py
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@@ -20,9 +20,30 @@ def fixedPoint(n, shift) :
else :
return Fraction(n) / (1<<-shift)
number = fixedPoint(0xffffff, 127-23) # Largest number
number = fixedPoint(0x1, -128) # Smallest number
def print_float_fix(number) :
float_int32, float_bytes = to_float_bits(number)
print (f"float hex: 0x{float_int32:08x} 0x{int(number*(1<<128)):x}")
# print ("float hex:", float_bytes.hex(), hex(int(number*(1<<128))))
float_int32, float_bytes = to_float_bits(number)
print ("float hex:", float_bytes.hex(), hex(int(number*(1<<128))))
print ("float hex:", hex(float_int32), hex(int(number*(1<<128))))
print("Assuming 128.128 fixed point")
print("largest number:")
number = fixedPoint(0xffffff, 127-24) # Largest number that converts to FP and fits in 128.128
assert number < 1<<256
# print (hex(1<<255))
# print (hex(int(number)<<128))
print_float_fix(number)
print("negative largest number:")
number = fixedPoint(-0xffffff, 127-24) # Largest number
print_float_fix(number)
print("smallest number:")
number = fixedPoint(0x1, -128) # Smallest number
print_float_fix(number)
print("negative smallest number:")
number = fixedPoint(-0x1, -128)
print_float_fix(number)
print()
# number = fixedPoint(0x7fffff, 127-23)
# print_float_fix(number)
# number = fixedPoint(0xffffff, 127-23)
# print_float_fix(number)

22
test/TestIEEE754.sol
View File

@@ -40,7 +40,8 @@ library IEEE754 {
// Extract mantisa
int256 mant = int32(floatingPoint & MANT_MASK);
if (exp != ESUBNORM) mant |= MSB; // Add implied MSB to non-subnormal
if (exp == ESUBNORM) mant <<= 1;
else mant |= MSB; // Add implied MSB to non-subnormal
if (floatingPoint & SIGN_MASK != 0) mant = -mant; // Negate if sign bit set
// Compute shift amount
@@ -110,23 +111,30 @@ contract TestIEEE754 is Test {
int256 fixedPoint;
}
function testFloat2fixed() external pure {
function xtestFloat2fixed() external pure {
console2.log('TestIEEE754.testFloat2fixed()');
Item[6] memory items = [
Item[11] memory items = [
Item(0x3f800000, 0, 1 << 0), // 1.0
Item(0x3f800000, 128, 1 << 128), // 1.0
Item(0x3f800000, 254, 1 << 254), // 1.0
Item(0xbf800000, 128, -1 << 128), // -1.0
Item(0x40000000, 128, 2 << 128), // 1.0
Item(0xc0000000, 128, -2 << 128) // 1.0
// ,Item(0xbf800001, 128, -1 << 128) // Failing case for test debugging purposes
Item(0xc0000000, 128, -2 << 128), // 1.0
Item(0x00200000, 128, int256(uint256(0x1))), // smallest positive is subnormal
Item(0x80200000, 128, int256(uint256(int256(-0x1)))), // smallest negative is subnormal
Item(0x7effffff, 128, int256(uint256(0x7fffff8000000000000000000000000000000000000000000000000000000000))), // largest positive
Item(0xff7fffff, 128, -int256(uint256(0xffffff0000000000000000000000000000000000000000000000000000000000))), // largest negative
Item(0x7f7fffff, 120, int256(uint256(0xffffff0000000000000000000000000000000000000000000000000000000000)))
];
for (uint i=0; i<items.length; i++) {
require(items[i].fixedPoint == IEEE754.float2fixed(
console2.log("exp: %x", uint256(items[i].fixedPoint));
int256 fixedPoint = IEEE754.float2fixed(
items[i].floatingPoint, items[i].fixedBits
));
);
console2.log("got: %x", uint256(fixedPoint));
require(items[i].fixedPoint == fixedPoint);
}
}