Decoding a PASCAL line of code

Question

I am new to PASCAL and I am working on a PASCAL code. I would really appreciate if somebody helped me understand this piece of code.

readagain1:     
        Write(' ', (BYWORD(fileio_dcb.usr_buf^[WRD((2*j)+1)], fileio_dcb.usr_buf^[WRD((2*j)+0)])):4:16);     
        Write(' ', (BYWORD(fileio_dcb.usr_buf^[WRD((2*j)+3)], fileio_dcb.usr_buf^[WRD((2*j)+2)])):4:16);     
        Write(' ', (BYWORD(fileio_dcb.usr_buf^[WRD((2*j)+5)], fileio_dcb.usr_buf^[WRD((2*j)+4)])):4:16);     
        Write(' ', (BYWORD(fileio_dcb.usr_buf^[WRD((2*j)+7)], fileio_dcb.usr_buf^[WRD((2*j)+6)])):4:16);     
        Write(' ', (BYWORD(fileio_dcb.usr_buf^[WRD((2*j)+9)], fileio_dcb.usr_buf^[WRD((2*j)+8)])):4:16);     
        Write(' ', (BYWORD(fileio_dcb.usr_buf^[WRD((2*j)+11)], fileio_dcb.usr_buf^[WRD((2*j)+10)])):4:16);     
        Write(' ', (BYWORD(fileio_dcb.usr_buf^[WRD((2*j)+13)], fileio_dcb.usr_buf^[WRD((2*j)+12)])):4:16);     
        WriteLn(' ', (BYWORD(fileio_dcb.usr_buf^[WRD((2*j)+15)], fileio_dcb.usr_buf^[WRD((2*j)+14)])):4:16);     
        j := j+8;     
        IF (j < 100) THEN GOTO readagain1;
        j := 0;     
        int_dcb.txt_buf.r := 0;     
        WriteLn;
        WriteLn('Reading txt_buf ; ');

readagain1 is a label that has already been declared.

Hexdecimal numbers are being read from a file into a buffer(fileio_dcb.usr_buf) ans some operation is being performed on the hex number read. I would appreciate any help with understanding the operation being performed on the number.

score 0 · Answer 1 · answered Apr 03 '14 at 13:44

My guess is that each iteration it writes out 13 (=100/8 rounded up) lines with 8 (16-bit) word sized hex numbers per line. Each line has a leading space.

It is probably an atypical (non Borland) dialect that can write hexvalues using :4:16 (I assume this means base 16, 4 digits wide). Most typical dialects (and the standard?) only use :x:y for floating point.

BYWORD() and WRD() are not standard identifiers, my guess this is some embedded dialect that combines two bytes into a word. Maybe it can only read words from aligned addresses, and are these builtins/macros workarounds for that.

Note that this is all based on "most likely it does that". The fragment is not complete enough, and the dialect not standard.

Decoding a PASCAL line of code

1 Answers1