/* Borland Pascal Win16 loader-register capture and runtime startup. */

#include "tdkpin_borland_startup.h"

enum {
    WIN_FLAG_CPU_086 = 0x40,
    WIN_FLAG_CPU_186 = 0x80,
    WIN_FLAG_CPU_286 = 0x02,
    BORLAND_HUGE_POINTER_INCREMENT = 8,
};

/*
 * 1020:0002 -- first Borland runtime call made by ne_program_entry.
 *
 * The NE loader supplies the process state in registers, so the readable C
 * interface packages those registers rather than pretending they were stack
 * arguments.  The original accepts only nonzero AX and a successful InitApp;
 * either failure executes INT 21h/AH=4ch with AL=ff and never returns.
 */
void borland_initialize_win16_runtime(
    const BorlandWin16StartupRegisters *registers)
{
    if (registers->loader_ax == 0) {
        win16_dos_terminate(0xff);
    }

    g_borland_windows_mode =
        win16_far_selector(registers->command_line);
    g_win16_previous_instance = registers->previous_instance;
    g_win16_instance = registers->instance;
    g_win16_show_command = registers->show_command;
    g_borland_command_line = registers->command_line;

    WaitEvent16(0);
    if (InitApp16(g_win16_instance) == 0) {
        win16_dos_terminate(0xff);
    }

    uint8_t flags = (uint8_t)GetWinFlags16();
    uint16_t cpu_level = 0;
    if ((flags & (WIN_FLAG_CPU_086 | WIN_FLAG_CPU_186)) == 0) {
        cpu_level++;
        if ((flags & WIN_FLAG_CPU_286) == 0) {
            cpu_level++;
        }
    }
    g_borland_cpu_level = (uint8_t)cpu_level;

    /* KERNEL ordinal 114 is the imported equate __AHINCR, not a call. */
    g_borland_huge_pointer_increment = BORLAND_HUGE_POINTER_INCREMENT;
}