/*
 * romapi.h -- the VT1200 firmware entry points a C payload may call.
 *
 * Every address here is a TMS34010 BIT address (= Ghidra byte address x 8).
 * The evidence for each is dwt/notes/TCPIP.md (sockets) and dwt/notes/HEAP.md
 * (allocator); the ones marked "verified live" have been called from a payload
 * on real hardware, not just read out of the ROM.
 *
 * K&R C only.  This compiler rejects ANSI prototypes (`int f(int a)` is a
 * syntax error), so the declarations below are old-style: the parameter lists
 * live in the comments, and the compiler checks nothing but the name.  That is
 * the price of using the 1987 toolchain; keep the comments honest.
 *
 * Calling convention: the C compiler and the firmware agree -- arguments are
 * widened to 32 bits and pushed upward on the program stack (A14), first
 * argument last, and the result comes back in A8.  The thunks in entry.asm
 * forward with `calla`, so the caller's already-pushed arguments pass through
 * untouched and only A8 has to survive.
 */
#ifndef ROMAPI_H
#define ROMAPI_H

/* ---- ROM entry points -------------------------------------------------- */
#define ROM_SOCKET       0x3F5C9A00   /* Ghidra 07EB9340  verified live */
#define ROM_BIND         0x3F5CAA80   /* Ghidra 07EB9550  BOOTP caller  */
#define ROM_LISTEN       0x3F5CBCD0   /* Ghidra 07EB979A  inetd caller  */
#define ROM_ACCEPT       0x3F5CCB40   /* Ghidra 07EB9968  inetd caller  */
#define ROM_SENDTO       0x3F5D3D70   /* Ghidra 07EBA7AE  verified live */
#define ROM_RECVFROM     0x3F5D7D50   /* Ghidra 07EBAFAA  verified live */
#define ROM_READ         0x3F5D8E70   /* Ghidra 07EBB1CE  rdebug / Xlib */
#define ROM_CLOSE        0x3F5E8930   /* Ghidra 07EBD126  verified live */
#define ROM_SETSOCKOPT   0x3F5DD260   /* Ghidra 07EBBA4C  BOOTP / Xlib   */
#define ROM_DELAY        0x3F833A20   /* Ghidra 07F66744  sleep(ms), telnet caller */
#define ROM_SELECT       0x3F871CE0   /* Ghidra 07F0E39C  Xlib caller, candidate */
#define ROM_MALLOC       0x3F701230   /* Ghidra 07EE0246  verified live */
#define ROM_FREE         0x3F702440   /* Ghidra 07EE0488  allocator     */
#define ROM_CREATE_PROC  0x3F706A40   /* Ghidra 07EE0D48  GUI work      */

/* ---- thunks implemented in entry.asm ----------------------------------- */
/*
 * int socket_(domain, type, protocol)          -> fd, or -1
 * int bind_(fd, sockaddr *, len)               -> 0, or -1
 * int recvfrom_(fd, buf, len, flags, from *, fromlen *)
 *                                              -> bytes, or -1
 * int close_(fd)                               -> 0, or -1
 * unsigned int malloc_(bytes)                  -> BIT pointer, or 0
 * int free_(bit pointer)                       -> 0
 *
 * `from` is a 16-byte sockaddr the stack fills in; `fromlen` points to an
 * int that must be 16 on entry (the call writes back the real length).
 */
int socket_();
int bind_();
int recvfrom_();
int close_();
int listen_();
int accept_();
int read_();
int select_();
int delay_();
unsigned int malloc_();
int free_();

/* ---- socket constants -------------------------------------------------- */
#define AF_INET      2
#define SOCK_DGRAM   2
#define SOCK_STREAM  1
#define IPPROTO_UDP  0

#define SOCKADDR_LEN 16
/*
 * struct sockaddr, 16 bytes, NETWORK byte order:
 *   +0  u16 family   (AF_INET = 2 -> bytes 00 02)
 *   +2  u16 port     (high byte first, e.g. 7000 = 0x1B58 -> 1B 58)
 *   +4  u32 addr     (0 = INADDR_ANY)
 *   +8  u8  zero[8]
 */

/* Fill sa (an unsigned char[16]) with AF_INET, `port`, and INADDR_ANY.
 * `port` is in host order so callers can write 7000 rather than 0x1B58. */
static void sa_any(sa, port)
unsigned char *sa;
unsigned int port;
{
    sa[0] = 0; sa[1] = AF_INET;
    sa[2] = (port >> 8) & 0xFF;
    sa[3] = port & 0xFF;
    sa[4] = 0; sa[5] = 0; sa[6] = 0; sa[7] = 0;
    sa[8] = 0; sa[9] = 0; sa[10] = 0; sa[11] = 0;
    sa[12] = 0; sa[13] = 0; sa[14] = 0; sa[15] = 0;
}

#endif /* ROMAPI_H */