Processing System Functions

All Turbo Pascal system functions are processed by this procedure. Each system function has a processing procedure and an optional parameter. This parameter is used when two or more functions share the same processing procedure.
Type TFunctions = Record
                    Proc: Procedure;
                    FuncParameter: Word;
                  end;

Const Functions: Array [$00..$33] of TFunctions = (
        (Proc: Func_New;                 FuncParameter: 0),                 { New }
        (Proc: Func_TextFunctions;       FuncParameter: SysProc_GetSEoln),  { SeekEoln }
        (Proc: Func_TextFunctions;       FuncParameter: SysProc_GetSEof),   { SeekEof }
        (Proc: Func_TextFunctions;       FuncParameter: SysProc_GetTEoln),  { Eoln }
        (Proc: Func_TextFunctions;       FuncParameter: SysProc_GetTEof),   { Eof }
        (Proc: Func_FilePos_FileSize;    FuncParameter: SysProc_GetFPos),   { FilePos }
        (Proc: Func_FilePos_FileSize;    FuncParameter: SysProc_GetFSize),  { FileSize }
        (Proc: Func_UpCase;              FuncParameter: 0),                 { UpCase }
        (Proc: Func_Abs;                 FuncParameter: 0),                 { Abs }
        (Proc: Func_Sqr;                 FuncParameter: 0),                 { Sqr }
        (Proc: Func_Succ_Pred;           FuncParameter: 1),                 { Succ }
        (Proc: Func_Succ_Pred;           FuncParameter: 0),                 { Pred }
        (Proc: Func_Odd;                 FuncParameter: 0),                 { Odd }
        (Proc: Func_Ord;                 FuncParameter: 0),                 { Ord }
        (Proc: Func_Chr;                 FuncParameter: 0),                 { Chr }
        (Proc: Func_Ptr;                 FuncParameter: 0),                 { Ptr }
        (Proc: Func_Addr_Ofs_Seg;        FuncParameter: 1),                 { Ofs }
        (Proc: Func_Addr_Ofs_Seg;        FuncParameter: 2),                 { Seg }
        (Proc: Func_Registers;           FuncParameter: MOV_AX_CS),         { CSeg }
        (Proc: Func_Registers;           FuncParameter: MOV_AX_DS),         { DSeg }
        (Proc: Func_Registers;           FuncParameter: MOV_AX_SS),         { SSeg }
        (Proc: Func_Registers;           FuncParameter: MOV_AX_SP),         { SPtr }
        (Proc: Func_SizeOf;              FuncParameter: 0),                 { SizeOf }
        (Proc: Func_ArithmeticFunctions; FuncParameter: 2),                 { Sqrt }
        (Proc: Func_ArithmeticFunctions; FuncParameter: 0),                 { Int }
        (Proc: Func_ArithmeticFunctions; FuncParameter: 3),                 { Sin }
        (Proc: Func_ArithmeticFunctions; FuncParameter: 4),                 { Cos }
        (Proc: Func_ArithmeticFunctions; FuncParameter: 7),                 { ArcTan }
        (Proc: Func_ArithmeticFunctions; FuncParameter: 5),                 { Ln }
        (Proc: Func_ArithmeticFunctions; FuncParameter: 6),                 { Exp }
        (Proc: Func_Trunc_Round;         FuncParameter: 8),                 { Trunc }
        (Proc: Func_Trunc_Round;         FuncParameter: 9),                 { Round }
        (Proc: Func_MemAvail_MaxAvail;   FuncParameter: SysProc_GetFreMem), { MemAvail }
        (Proc: Func_MemAvail_MaxAvail;   FuncParameter: SysProc_GetFreMax), { MaxAvail }
        (Proc: Func_Length;              FuncParameter: 0),                 { Length }
        (Proc: Func_Pos;                 FuncParameter: 0),                 { Pos }
        (Proc: Func_Copy;                FuncParameter: 0),                 { Copy }
        (Proc: Func_Concat;              FuncParameter: 0),                 { Concat }
        (Proc: Func_IOResult_ParamCount; FuncParameter: SysProc_GetIORes),  { IOResult }
        (Proc: Func_ArithmeticFunctions; FuncParameter: 1),                 { Frac }
        (Proc: Func_Random;              FuncParameter: 0),                 { Random }
        (Proc: Func_ParamStr;            FuncParameter: 0),                 { ParamStr }
        (Proc: Func_IOResult_ParamCount; FuncParameter: SysProc_GetParCnt), { ParamCount }
        (Proc: Func_Lo;                  FuncParameter: 0),                 { Lo }
        (Proc: Func_Hi;                  FuncParameter: 0),                 { Hi }
        (Proc: Func_Swap;                FuncParameter: 0),                 { Swap }
        (Proc: Func_Pi;                  FuncParameter: 0),                 { Pi }
        (Proc: Func_Addr_Ofs_Seg;        FuncParameter: 0),                 { Addr }
        (Proc: Func_TypeOf;              FuncParameter: 0),                 { TypeOf }
        (Proc: Func_Assigned;            FuncParameter: 0),                 { Assigned }
        (Proc: Func_Low_High;            FuncParameter: 8),                 { Low }
        (Proc: Func_Low_High;            FuncParameter: 12));               { High }
This procedure processes system functions. The parameter is saved to allow recursion calls.
Procedure ProcessFunction (Func: Byte; Var FunctionExpression: TExpression);
Var SavedExpression: PExpression;
    SavedParameter: Word;
begin
  SavedParameter := FuncParameter;
  FuncParameter := Functions [Func].FuncParameter;
  SavedExpression := Expression;
  Expression := @FunctionExpression;
  Functions [Func].Proc;
  Expression := SavedExpression;
  FuncParameter := SavedParameter;
end;
 
 
 
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