A-Shell Reference

Floating Point

F,4

32 bit IEEE float

F,6

48 bit AMOS float

F,8

64 bit IEEE float

Binary, little endian

B,1

8 bit unsigned

B,2

16 bit unsigned

B,3

24 bit unsigned

B,4

32 bit unsigned

B,5

40 bit signed (two's complement)

B,6

48 bit unsigned

I,6

48 bit signed (two's complement)

Integer

I,1

8 bit signed (two’s complement)

I,2

16 bit signed (two’s complement, little-endian)

I,4

32 bit signed (two’s complement, 2301 order)

String

S,#

fixed length string of # bytes

S,0

variable length string (dynamically sized, always with trailing null)

Unformatted
(raw bytes)

X,#

fixed length raw bytes

(none)

May be declared implicitly by leaving type,size specifier in MAP statement blank and defining lower-level MAP Statements.

Multi-level MAPs

MAP1 CUST
   MAP2 NAME,S,30
   MAP2 CUSNO,B,4
   MAP2 TOTSALES,F,6

READ #CH, CUST       ! read/write entire group as a unit

? NAME               ! individual fields referenced by name

1, 2

DEFSTRUCT

DEFSTRUCT ST_CUST    ! define structure layout
   MAP2 NAME,S,30
   MAP2 CUSNO,B,4
   MAP2 TOTSALES,F,6
ENDSTRUCT
...
MAP1 CUSREC,ST_CUST  ! define instance of structure
...
READ #CH, CUSREC     ! read/write entire struct at once
? CUSREC.NAME        ! use structvar.member notation for fields

DYNSTRUCT

MAP1 DS, DYNSTRUCT