# 29-ascii-ebcdic: ASCII to EBCDIC Encoding Conversion

## 电信业务场景

ASCII→EBCDIC主机编码转换。通过内建转换表将ASCII编码的CDR数据转换为EBCDIC编码，用于与大型主机系统交换数据。

## Description

Reads an ASCII-encoded sequential file and converts each byte to its
EBCDIC equivalent using an internal conversion table defined via
REDEFINES. The output file contains the EBCDIC-encoded data.

**Note:** GnuCOBOL internally uses ASCII encoding. This program
demonstrates a manual encoding conversion algorithm for scenarios
where EBCDIC output is required for legacy system compatibility.

## Conversion Table

The 128-entry ASCII-to-EBCDIC table is initialized from REDEFINES
data at program start. It covers:

- Control characters (X'00'-X'3F') mapped to their EBCDIC equivalents
- Printable characters (X'20'-X'7F') mapped per standard conversion
- Characters >= X'80' are passed through unchanged

## Record Layout

### Input / Output (80 bytes fixed-length)

| Structure | Type     | Description                          |
|-----------|----------|--------------------------------------|
| IN-BYTE   | OCCURS   | Individual bytes for conversion      |

## Files

| File                    | Purpose                        |
|-------------------------|--------------------------------|
| main-29-ascii-ebcdic.cbl | Main COBOL program            |
| data-gen.sh             | Generate ASCII test data       |
| run.sh                  | Compile, run, verify           |
| README.md               | This file                      |

## Tests

| Test Case                  | Description                        |
|----------------------------|------------------------------------|
| Uppercase A-Z              | Letters mapped to EBCDIC           |
| Lowercase a-z              | Lowercase mapped to EBCDIC         |
| Digits 0-9                 | Numeric characters converted       |
| Printable symbols          | Symbols like !@#$% converted       |
| Mixed content              | Combination of letters/numbers     |
| Control characters         | Preserved through conversion       |
| Space-padded record        | Padding character handling         |
| All printable chars        | Full ASCII printable range test    |

## Usage

```bash
cd 29-ascii-ebcdic
bash data-gen.sh
bash run.sh
```

## Expected Behavior

- Input and output are the same size (8 records x 80 bytes each).
- ASCII character 'A' (X'41') maps to EBCDIC X'C1'.
- ASCII character '0' (X'30') maps to EBCDIC X'F0'.
- Control characters (X'00'-X'1F') are converted per EBCDIC mapping.
- Non-ASCII bytes (>= X'80') pass through unchanged.