(*
    BSD 2-Clause License

    Copyright (c) 2019-2020, Anton Krotov
    All rights reserved.
*)

MODULE LINAPI;

IMPORT SYSTEM, API, Libdl;


TYPE

    TP* = ARRAY 2 OF INTEGER;
    SOFINI* = PROCEDURE;


VAR

    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 SetFini* (ProcFini: SOFINI);
BEGIN
    API.SetFini(ProcFini)
END SetFini;


PROCEDURE GetSym (lib: INTEGER; name: ARRAY OF CHAR; VarAdr: INTEGER);
VAR
    sym: INTEGER;

BEGIN
    sym := Libdl.sym(lib, name);
    ASSERT(sym # 0);
    SYSTEM.PUT(VarAdr, sym)
END GetSym;


PROCEDURE init;
BEGIN
    libc := API.libc;

    GetSym(libc, "exit",   SYSTEM.ADR(exit));
    GetSym(libc, "puts",   SYSTEM.ADR(puts));
    GetSym(libc, "malloc", SYSTEM.ADR(malloc));
    GetSym(libc, "free",   SYSTEM.ADR(free));
    GetSym(libc, "fread",  SYSTEM.ADR(fread));
    GetSym(libc, "fwrite", SYSTEM.ADR(fwrite));
    GetSym(libc, "fopen",  SYSTEM.ADR(fopen));
    GetSym(libc, "fclose", SYSTEM.ADR(fclose));
    GetSym(libc, "time",   SYSTEM.ADR(time));

    GetSym(libc, "stdout", SYSTEM.ADR(stdout)); SYSTEM.GET(stdout - SYSTEM.SIZE(INTEGER), stdout);
    GetSym(libc, "stdin",  SYSTEM.ADR(stdin));  SYSTEM.GET(stdin  - SYSTEM.SIZE(INTEGER), stdin);
    GetSym(libc, "stderr", SYSTEM.ADR(stderr)); SYSTEM.GET(stderr - SYSTEM.SIZE(INTEGER), stderr);

    librt := Libdl.open("librt.so.1", Libdl.LAZY);

    GetSym(librt, "clock_gettime", SYSTEM.ADR(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.