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Fix hilo.p for big-endian platforms.

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Unless it is packed, a Pascal char is a C int.  Using C types, hilo.p
passed an int *buf to uread(), which expected a char *buf.  Then
uread() wrote the char on the end of the int.  This worked on
little-endian platforms.  This failed on big-endian platforms, as
writing the value to the big end of an int multiplied it by 16777216.

The fix is to use a packed array [0..0] of char in Pascal.  I also
change 'string' to a packed array, though this is not a necessary part
of the fix.
This commit is contained in:
George Koehler 2016-09-18 00:07:30 -04:00
parent 03b067e1d5
commit e4ce7da0a2
1 changed files with 6 additions and 5 deletions
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11
examples/hilo.p
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@ -8,7 +8,8 @@
program hilo(input, output); program hilo(input, output);
type type
string = array [0..255] of char; string = packed array [0..255] of char;
charstar = packed array [0..0] of char;
var var
playing : Boolean; playing : Boolean;
@ -34,18 +35,18 @@ function random(range : integer) : integer;
that conflicts with a Pascal keyword. Luckily there's a private function that conflicts with a Pascal keyword. Luckily there's a private function
uread() in the ACK Pascal library that we can use instead. } uread() in the ACK Pascal library that we can use instead. }
function uread(fd : integer; var buffer : char; count : integer) : integer; function uread(fd : integer; var buffer : charstar; count : integer) : integer;
extern; extern;
function readchar : char; function readchar : char;
var var
c : char; c : charstar;
dummy : integer; dummy : integer;
begin begin
c := chr(0); c[0] := chr(0);
dummy := uread(0, c, 1); dummy := uread(0, c, 1);
readchar := c; readchar := c[0];
end; end;
procedure readstring(var buffer : string; var length : integer); procedure readstring(var buffer : string; var length : integer);