pystdf4 0.1.0

A Python library for reading and writing STDF4 files

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pystdf4

An object-oriented Python library for parsing and generating STDF (Standard Test Data Format) files used in semiconductor testing and manufacturing.

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🧩 Overview

pystdf4 provides a modern, object-oriented interface for working with STDF v4 files — the industry-standard binary data format for semiconductor test results. It supports both reading and writing of STDF files, with a clean Python API that abstracts low-level binary details into high-level Pythonic objects.

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📘 STDF4 Data Type Codes

The Standard Test Data Format (STDF) specification defines compact type codes to describe how values are stored and interpreted within records. Each type code corresponds to a C data type, defining the byte layout and valid range of values.

Code	Description	C Type Specifier	Notes
C*1	Fixed-length character string (1 characters)	char[1]	Left-justified; pad with spaces if shorter than 12 characters.
C*n	Variable-length character string	char[]	First byte stores the length (0–255).
C*f	Variable-length string with external length	char[]	Length determined by another record field.
U*1	1-byte unsigned integer	unsigned char	Range: 0–255
U*2	2-byte unsigned integer	unsigned short	Range: 0–65,535
U*4	4-byte unsigned integer	unsigned long	Range: 0–4,294,967,295
I*1	1-byte signed integer	char	Range: –128 to 127
I*2	2-byte signed integer	short	Range: –32,768 to 32,767
I*4	4-byte signed integer	long	Range: –2,147,483,648 to 2,147,483,647
R*4	4-byte floating-point number (IEEE 754)	float	Standard single-precision float
R*8	8-byte floating-point number (IEEE 754)	double	Standard double-precision float
B*6	Fixed-length binary field (6 bytes)	char[6]	Raw binary data
V*n	Variable-type field	—	First byte = type code, followed by up to 255 bytes of data
B*n	Variable-length binary field	char[]	First byte = byte count (0–255); data starts at LSB of second byte
D*n	Variable-length bit field	char[]	First two bytes = bit count (0–65,535); unused bits in last byte = 0
N*1	Nibble (4-bit) data	char	Stores unsigned integers in 4-bit units; high nibble zeroed if odd count
kxTYPE	Array of specified data type	TYPE[]	Length k determined by another record field (e.g. kxU*2)

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🧱 PyStdf4 Data Model

The PyStdf4 type system provides a structured, extensible way to represent STDF data elements as Python classes. Each class encapsulates type conversion, byte parsing, and STDF serialization.

Field (ABC)
├── ScalarField[_PyT]
│   ├── U_1, U_2, U_4       # unsigned int
│   ├── I_1, I_2, I_4       # signed int
│   ├── R_4, R_8            # float
│   ├── C_1                 # char → bytes
│   └── B_1                 # raw bytes
└── SequenceField[_PyT] (ABC)
    ├── FixLenField[_PyT]
    ├── VarLenField[_PyT]
    │   ├── C_n (str → bytes)
    │   └── B_n (bytes)
    └── KxLenField
        ├── KxU_1
        ├── KxU_2
        ├── KxC_n
        └── KxR_4

These classes standardize how data flows between Python, C-style internal representations, and STDF binary data.

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🔄 Data Flow

The transformation pipeline for STDF data in pystdf4 can be summarized as follows:

py_value (Python type)
   ⇄ [build_py / parse_py]
internal_bytes (C-style binary data)
   ⇄ [build_stdf / parse_stdf]
stdf_value (STDF field data)

This design ensures each data element can:

• be parsed from STDF binary files,
• be converted into native Python types for analysis or manipulation,
• and be re-serialized back into valid STDF format.

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📋 STDF v4 Record Types Implementation Status

Record Type	Name	REC_TYP	REC_SUB	Status	Notes
FAR	File Attributes Record	0	10	✔️ Complete	Required as first record
ATR	Audit Trail Record	0	20	✔️ Complete	Tracks file modifications
MIR	Master Information Record	1	10	✔️ Complete	Lot-level information
MRR	Master Results Record	1	20	✔️ Complete	End of lot summary
PCR	Part Count Record	1	30	✔️ Complete	Part statistics
HBR	Hardware Bin Record	1	40	✔️ Complete	Physical binning counts
SBR	Software Bin Record	1	50	✔️ Complete	Logical binning counts
PMR	Pin Map Record	1	60	✔️ Complete	Pin/channel mapping
PGR	Pin Group Record	1	62	❌ Incomplete	Pin grouping
PLR	Pin List Record	1	63	❌ Incomplete	Pin group display properties
RDR	Retest Data Record	1	70	❌ Incomplete	Retest information
SDR	Site Description Record	1	80	✔️ Complete	Test site configuration
WIR	Wafer Information Record	2	10	✔️ Complete	Wafer start marker
WRR	Wafer Results Record	2	20	✔️ Complete	Wafer completion summary
WCR	Wafer Configuration Record	2	30	✔️ Complete	Wafer dimensions/orientation
PIR	Part Information Record	5	10	✔️ Complete	Part start marker
PRR	Part Results Record	5	20	✔️ Complete	Part completion results
TSR	Test Synopsis Record	10	30	✔️ Complete	Test execution statistics
PTR	Parametric Test Record	15	10	✔️ Complete	Single parametric test result
MPR	Multiple-Result Parametric Record	15	15	❌ Incomplete	Multiple parametric test results
FTR	Functional Test Record	15	20	❌ Incomplete	Functional test results
BPS	Begin Program Section Record	20	10	✔️ Complete	Program section start marker
EPS	End Program Section Record	20	20	✔️ Complete	Program section end marker
GDR	Generic Data Record	50	10	❌ Incomplete	User-defined data
DTR	Datalog Text Record	50	30	❌ Incomplete	Datalog comments

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🧪 Example Use Cases (Coming Soon)

• Parse STDF records into structured Python objects
• Convert STDF to human-readable CSV or JSON
• Build new STDF records programmatically
• Validate field encoding/decoding across STDF revisions

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📜 License

MIT License © 2025 Developed for efficient and reliable STDF data manipulation in modern semiconductor workflows.

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Would you like me to extend it with an “Installation and Quick Start” section (e.g., pip install pystdf4 and a short usage example)? That would make it more complete for public release on GitHub or PyPI.