unit FMRepeater;

{ FM repeater offset helpers — constants, default offsets, auto-direction logic. }

{$mode objfpc}{$H+}

interface

const
  RPT_NONE  = 0;
  RPT_MINUS = 1;
  RPT_PLUS  = 2;

  RPT_2M_BEGIN     = 144000000.0;
  RPT_2M_END       = 148000000.0;
  RPT_70CM_BEGIN   = 430000000.0;
  RPT_70CM_END     = 440000000.0;
  RPT_DEFAULT_2M   =   600000.0;  // 0.600 MHz
  RPT_DEFAULT_70CM = 7600000.0;   // 7.600 MHz

  // European 2m repeater input segment: auto-enable minus direction
  RPT_AUTO_MINUS_LO = 145600000.0;  // 145.600 MHz
  RPT_AUTO_MINUS_HI = 145787500.0;  // 145.7875 MHz

{ Returns default offset (Hz) for the given visible frequency.
  70 cm band → 7.600 MHz; everything else → 0.600 MHz. }
function RptDefaultOffsetHz(FreqHz: Double): Double;

{ Returns RPT_MINUS when FreqHz falls in the 2 m auto-minus segment,
  RPT_NONE otherwise. }
function RptAutoDir(FreqHz: Double): Integer;

{ Formats OffsetHz as MHz with 3 decimal places, e.g. "0.600". }
function RptFormatOffset(OffsetHz: Double): string;

{ Parses a MHz string ("0.600", "7.6", "7,600") to Hz.
  Returns 0 on parse error or out-of-range value. }
function RptParseOffset(const S: string): Double;

implementation

uses SysUtils;

function RptDefaultOffsetHz(FreqHz: Double): Double;
begin
  if (FreqHz >= RPT_70CM_BEGIN) and (FreqHz <= RPT_70CM_END) then
    Result := RPT_DEFAULT_70CM
  else
    Result := RPT_DEFAULT_2M;
end;

function RptAutoDir(FreqHz: Double): Integer;
begin
  if (FreqHz >= RPT_AUTO_MINUS_LO) and (FreqHz <= RPT_AUTO_MINUS_HI) then
    Result := RPT_MINUS
  else
    Result := RPT_NONE;
end;

function RptFormatOffset(OffsetHz: Double): string;
begin
  Result := Format('%.3f', [OffsetHz / 1000000.0]);
end;

function RptParseOffset(const S: string): Double;
var
  V:    Double;
  Code: Integer;
  Norm: string;
begin
  Norm := StringReplace(Trim(S), ',', '.', [rfReplaceAll]);
  Val(Norm, V, Code);
  if (Code = 0) and (V > 0.0) and (V <= 100.0) then
    Result := V * 1000000.0
  else
    Result := 0.0;
end;

end.