imas.util.calc_hash¶

imas.util.calc_hash(node: IDSBase) → bytes¶

Calculate the hash of the provided IDS object.

Hashes are calculated as follows:

1. Data nodes:

   1. STR_0D: hash of value (encoded as UTF-8)

   2. STR_1D: hash of concatenation of

      • Length of the STR_1D (64-bit little-endian integer)

      • hash of value[0] (encoded as UTF-8)

      • hash of value[1] (encoded as UTF-8)

      • …

   3. INT_0D: hash of value (32-bit little-endian signed integer)

   4. FLT_0D: hash of value (64-bit IEEE 754 floating point number)

   5. CPX_0D: hash of value (128-bit: real, imag)

   6. ND arrays: hash of concatenation of

      • Dimension (8-bit integer)

      • Shape (dimension * 64-bits little-endian integer)

      • Concatenated data (little-endian, Fortran memory layout)

2. Array of structures nodes: hash of concatenation of

   • Length of the AoS (64-bit little-endian integer)

   • Hash of structure[0]

   • Hash of structure[1]

   • …

3. Structure nodes:

   1. Sort all children alphabetically

   2. Remove empty children. Children are empty when:

      • INT_0D: equal to EMPTY_INT

      • FLT_0D: equal to EMPTY_FLOAT

      • CPX_0D: equal to EMPTY_COMPLEX

      • ND arrays: array is empty

      • STR_0D: equal to ""

      • STR_1D: length is 0

      • Array of structures: length is 0

      • Structure: all children are empty

   3. Remove ids_properties/version_put structure

   4. Calculate hash of concatenation of

      • Name of child[0] (encoded as UTF-8)

      • Hash of child[0]

      • …

The hash function used is xxhash.xxh3_64 from the xxhash package.

Example

cp = imas.IDSFactory().core_profiles()
cp.ids_properties.homogeneous_time = 0

print(imas.util.calc_hash(cp).hex())  # 3b9b929756a242fd