gnucobol-rs-io vs gnucobol-rs-bdb-format vs gnucobol-rs

gnucobol-rs file subsystem: real OS file I/O for fixed-record RECORD/LINE SEQUENTIAL COBOL files over the oracle-proven gnucobol-rs record + FILE STATUS primitives.

Pure-safe-Rust reader AND writer for the Berkeley DB B-tree on-disk file format GnuCOBOL uses for INDEXED (ISAM) files. Clean-room from the public DB page layout: reads key->record pairs from a .dat written by real GnuCOBOL/libdb, and writes a .dat the genuine cobc can OPEN and READ. No unsafe, no C/libdb linkage.

Faithful Rust port of GnuCOBOL packed-decimal (COMP-3), zoned, and display numeric byte semantics and the MOVE conversions between them, proven byte-identical against the GnuCOBOL 3.2 libcob oracle. Plus a PIC->field-model parser , DATA DIVISION record-layout engine, , COPY+REPLACING copybook expander, pure-Rust decimal arithmetic, VALUE initial-record images, PIC P-scaling, OCCURS DEPENDING ON physical-max layout, LEVEL-88 condition-name predicates, and SET-TO-TRUE byte construction. Not a compiler; not arithmetic.