(*
    BSD 2-Clause License

    Copyright (c) 2019, Anton Krotov
    All rights reserved.
*)

MODULE LINAPI;

IMPORT SYSTEM, API;


TYPE

    TP* = API.TP;


VAR

    argc*, envc*: INTEGER;

    libc*, librt*: INTEGER;

    stdout*,
    stdin*,
    stderr*        : INTEGER;

    malloc*        : PROCEDURE [linux] (size: INTEGER): INTEGER;
    free*          : PROCEDURE [linux] (ptr: INTEGER);
    exit*          : PROCEDURE [linux] (code: INTEGER);
    puts*          : PROCEDURE [linux] (pStr: INTEGER);
    fwrite*,
    fread*         : PROCEDURE [linux] (buffer, bytes, blocks, file: INTEGER): INTEGER;
    fopen*         : PROCEDURE [linux] (fname, fmode: INTEGER): INTEGER;
    fclose*        : PROCEDURE [linux] (file: INTEGER): INTEGER;
    time*          : PROCEDURE [linux] (ptr: INTEGER): INTEGER;

    clock_gettime* : PROCEDURE [linux] (clock_id: INTEGER; VAR tp: TP): INTEGER;


PROCEDURE GetArg* (n: INTEGER; VAR s: ARRAY OF CHAR);
VAR
    i, len, ptr: INTEGER;
    c: CHAR;

BEGIN
    i := 0;
    len := LEN(s) - 1;
    IF (0 <= n) & (n <= argc + envc) & (n # argc) & (len > 0) THEN
        SYSTEM.GET(API.MainParam + (n + 1) * SYSTEM.SIZE(INTEGER), ptr);
        REPEAT
            SYSTEM.GET(ptr, c);
            s[i] := c;
            INC(i);
            INC(ptr)
        UNTIL (c = 0X) OR (i = len)
    END;
    s[i] := 0X
END GetArg;


PROCEDURE GetEnv* (n: INTEGER; VAR s: ARRAY OF CHAR);
BEGIN
    IF (0 <= n) & (n < envc) THEN
        GetArg(n + argc + 1, s)
    ELSE
        s[0] := 0X
    END
END GetEnv;


PROCEDURE init;
VAR
    ptr: INTEGER;

BEGIN
    envc := -1;
    SYSTEM.GET(API.MainParam, argc);
    REPEAT
        SYSTEM.GET(API.MainParam + (envc + argc + 3) * SYSTEM.SIZE(INTEGER), ptr);
        INC(envc)
    UNTIL ptr = 0;

    libc := API.libc;

    stdout := API.stdout;
    stdin  := API.stdin;
    stderr := API.stderr;

    malloc := API.malloc;
    free   := API.free;
    exit   := API._exit;
    puts   := API.puts;
    fwrite := API.fwrite;
    fread  := API.fread;
    fopen  := API.fopen;
    fclose := API.fclose;
    time   := API.time;

    librt := API.librt;

    clock_gettime := API.clock_gettime
END init;


PROCEDURE [stdcall-] syscall* (eax, ebx, ecx, edx, esi, edi: INTEGER): INTEGER;
BEGIN
    SYSTEM.CODE(
    053H,               (*  push    ebx                    *)
    056H,               (*  push    esi                    *)
    057H,               (*  push    edi                    *)
    08BH, 045H, 008H,   (*  mov     eax, dword [ebp +  8]  *)
    08BH, 05DH, 00CH,   (*  mov     ebx, dword [ebp + 12]  *)
    08BH, 04DH, 010H,   (*  mov     ecx, dword [ebp + 16]  *)
    08BH, 055H, 014H,   (*  mov     edx, dword [ebp + 20]  *)
    08BH, 075H, 018H,   (*  mov     esi, dword [ebp + 24]  *)
    08BH, 07DH, 01CH,   (*  mov     edi, dword [ebp + 28]  *)
    0CDH, 080H,         (*  int     128                    *)
    05FH,               (*  pop     edi                    *)
    05EH,               (*  pop     esi                    *)
    05BH,               (*  pop     ebx                    *)
    0C9H,               (*  leave                          *)
    0C2H, 018H, 000H    (*  ret     24                     *)
    )
    RETURN 0
END syscall;


BEGIN
    init
END LINAPI.