ssp16.c

/*
   basic, incomplete SSP160x (SSP1601?) interpreter
   with SVP memory controller emu

   (c) Copyright 2008, Grazvydas "notaz" Ignotas
   Free for non-commercial use.

   For commercial use, separate licencing terms must be obtained.

   Modified for Genesis Plus GX (Eke-Eke), added big endian support, fixed mode & addr
*/


/*
 * Register info
 *
 * 0. "-"
 *   size: 16
 *   desc: Constant register with all bits set (0xffff).
 *
 * 1. "X"
 *   size: 16
 *   desc: Generic register. When set, updates P (P = X * Y * 2)
 *
 * 2. "Y"
 *   size: 16
 *   desc: Generic register. When set, updates P (P = X * Y * 2)
 *
 * 3. "A"
 *   size: 32
 *   desc: Accumulator.
 *
 * 4. "ST"
 *   size: 16
 *   desc: Status register. From MAME: bits 0-9 are CONTROL, other FLAG
 *     fedc ba98 7654 3210
 *       210 - RPL (?)       "Loop size". If non-zero, makes (rX+) and (rX-) respectively
 *                           modulo-increment and modulo-decrement. The value shows which
 *                           power of 2 to use, i.e. 4 means modulo by 16.
 *                           (e: fir16_32.sc, IIR_4B.SC, DECIM.SC)
 *       43  - RB (?)
 *       5   - GP0_0 (ST5?)  Changed before acessing PM0 (affects banking?).
 *       6   - GP0_1 (ST6?)  Cleared before acessing PM0 (affects banking?). Set after.
 *                           datasheet says these (5,6) bits correspond to hardware pins.
 *       7   - IE (?)        Not directly used by SVP code (never set, but preserved)?
 *       8   - OP (?)        Not used by SVP code (only cleared)? (MAME: saturated value
 *                           (probably means clamping? i.e. 0x7ffc + 9 -> 0x7fff))
 *       9   - MACS (?)      Not used by SVP code (only cleared)? (e: "mac shift")
 *       a   - GPI_0         Interrupt 0 enable/status?
 *       b   - GPI_1         Interrupt 1 enable/status?
 *       c   - L             L flag. Carry?
 *       d   - Z             Zero flag.
 *       e   - OV            Overflow flag.
 *       f   - N             Negative flag.
 *     seen directly changing code sequences:
 *       ldi ST, 0      ld  A, ST     ld  A, ST     ld  A, ST     ldi st, 20h
 *       ldi ST, 60h    ori A, 60h    and A, E8h    and A, E8h
 *                      ld  ST, A     ld  ST, A     ori 3
 *                                                  ld  ST, A
 *
 * 5. "STACK"
 *   size: 16
 *   desc: hw stack of 6 levels (according to datasheet)
 *
 * 6. "PC"
 *   size: 16
 *   desc: Program counter.
 *
 * 7. "P"
 *   size: 32
 *   desc: multiply result register. P = X * Y * 2
 *         probably affected by MACS bit in ST.
 *
 * 8. "PM0" (PM from PMAR name from Tasco's docs)
 *   size: 16?
 *   desc: Programmable Memory access register.
 *         On reset, or when one (both?) GP0 bits are clear,
 *         acts as status for XST, mapped at 015004 at 68k side:
 *         bit0: ssp has written something to XST (cleared when 015004 is read)
 *         bit1: 68k has written something through a1500{0|2} (cleared on PM0 read)
 *
 * 9. "PM1"
 *   size: 16?
 *   desc: Programmable Memory access register.
 *         This reg. is only used as PMAR.
 *
 * 10. "PM2"
 *   size: 16?
 *   desc: Programmable Memory access register.
 *         This reg. is only used as PMAR.
 *
 * 11. "XST"
 *   size: 16?
 *   desc: eXternal STate. Mapped to a15000 and a15002 at 68k side.
 *         Can be programmed as PMAR? (only seen in test mode code)
 *         Affects PM0 when written to?
 *
 * 12. "PM4"
 *   size: 16?
 *   desc: Programmable Memory access register.
 *         This reg. is only used as PMAR. The most used PMAR by VR.
 *
 * 13. (unused by VR)
 *
 * 14. "PMC" (PMC from PMAC name from Tasco's docs)
 *   size: 32?
 *   desc: Programmable Memory access Control. Set using 2 16bit writes,
 *         first address, then mode word. After setting PMAC, PMAR sould
 *         be blind accessed (ld -, PMx  or  ld PMx, -) to program it for
 *         reading and writing respectively.
 *         Reading the register also shifts it's state (from "waiting for
 *         address" to "waiting for mode" and back). Reads always return
 *         address related to last PMx register accressed.
 *         (note: addresses do not wrap).
 *
 * 15. "AL"
 *   size: 16
 *   desc: Accumulator Low. 16 least significant bits of accumulator.
 *         (normally reading acc (ld X, A) you get 16 most significant bits).
 *
 *
 * There are 8 8-bit pointer registers rX. r0-r3 (ri) point to RAM0, r4-r7 (rj) point to RAM1.
 * They can be accessed directly, or 2 indirection levels can be used [ (rX), ((rX)) ],
 * which work similar to * and ** operators in C, only they use different memory banks and
 * ((rX)) also does post-increment. First indirection level (rX) accesses RAMx, second accesses
 * program memory at address read from (rX), and increments value in (rX).
 *
 * r0,r1,r2,r4,r5,r6 can be modified [ex: ldi r0, 5].
 * 3 modifiers can be applied (optional):
 *  + : post-increment [ex: ld a, (r0+) ]. Can be made modulo-increment by setting RPL bits in ST.
 *  - : post-decrement. Can be made modulo-decrement by setting RPL bits in ST (not sure).
 *  +!: post-increment, unaffected by RPL (probably).
 * These are only used on 1st indirection level, so things like [ld a, ((r0+))] and [ld X, r6-]
 * ar probably invalid.
 *
 * r3 and r7 are special and can not be changed (at least Samsung samples and SVP code never do).
 * They are fixed to the start of their RAM banks. (They are probably changeable for ssp1605+,
 * Samsung's old DSP page claims that).
 * 1 of these 4 modifiers must be used (short form direct addressing?):
 *  |00: RAMx[0] [ex: (r3|00), 0] (based on sample code)
 *  |01: RAMx[1]
 *  |10: RAMx[2] ? maybe 10h? accortding to Div_c_dp.sc, 2
 *  |11: RAMx[3]
 *
 *
 * Instruction notes
 *
 * ld a, * doesn't affect flags! (e: A_LAW.SC, Div_c_dp.sc)
 *
 * mld (rj), (ri) [, b]
 *   operation: A = 0; P = (rj) * (ri)
 *   notes: based on IIR_4B.SC sample. flags? what is b???
 *
 * mpya (rj), (ri) [, b]
 *   name: multiply and add?
 *   operation: A += P; P = (rj) * (ri)
 *
 * mpys (rj), (ri), b
 *   name: multiply and subtract?
 *   notes: not used by VR code.
 *
 * mod cond, op
 *   mod cond, shr  does arithmetic shift
 *
 * 'ld -, AL' and probably 'ld AL, -' are for dummy assigns
 *
 * memory map:
 * 000000 - 1fffff   ROM, accessable by both
 * 200000 - 2fffff   unused?
 * 300000 - 31ffff   DRAM, both
 * 320000 - 38ffff   unused?
 * 390000 - 3907ff   IRAM. can only be accessed by ssp?
 * 390000 - 39ffff   similar mapping to "cell arrange" in Sega CD, 68k only?
 * 3a0000 - 3affff   similar mapping to "cell arrange" in Sega CD, a bit different
 *
 * 30fe02 - 0 if SVP busy, 1 if done (set by SVP, checked and cleared by 68k)
 * 30fe06 - also sync related.
 * 30fe08 - job number [1-12] for SVP. 0 means no job. Set by 68k, read-cleared by SVP.
 *
 * + figure out if 'op A, P' is 32bit (nearly sure it is)
 * * does mld, mpya load their operands into X and Y?
 * * OP simm
 *
 * Assumptions in this code
 *   P is not directly writeable
 *   flags correspond to full 32bit accumulator
 *   only Z and N status flags are emulated (others unused by SVP)
 *   modifiers for 'OP a, ri' are ignored (invalid?/not used by SVP)
 *   'ld d, (a)' loads from program ROM
 */

#include "shared.h"


#define u32 unsigned int

/*#define USE_DEBUGGER*/

/* 0 */
#define rX     ssp->gr[SSP_X].byte.h
#define rY     ssp->gr[SSP_Y].byte.h
#define rA     ssp->gr[SSP_A].byte.h
#define rST    ssp->gr[SSP_ST].byte.h  /* 4 */
#define rSTACK ssp->gr[SSP_STACK].byte.h
#define rPC    ssp->gr[SSP_PC].byte.h
#define rP     ssp->gr[SSP_P]
#define rPM0   ssp->gr[SSP_PM0].byte.h  /* 8 */
#define rPM1   ssp->gr[SSP_PM1].byte.h
#define rPM2   ssp->gr[SSP_PM2].byte.h
#define rXST   ssp->gr[SSP_XST].byte.h
#define rPM4   ssp->gr[SSP_PM4].byte.h  /* 12 */
/* 13 */
#define rPMC   ssp->gr[SSP_PMC]    /* will keep addr in .h, mode in .l */
#define rAL    ssp->gr[SSP_A].byte.l

#define rA32   ssp->gr[SSP_A].v
#define rIJ    ssp->ptr.r

#define IJind  (((op>>6)&4)|(op&3))

#define GET_PC() (PC - (unsigned short *)svp->iram_rom)
#define GET_PPC_OFFS() ((unsigned int)PC - (unsigned int)svp->iram_rom - 2)
#define SET_PC(d) PC = (unsigned short *)svp->iram_rom + d

#define REG_READ(r) (((r) <= 4) ? ssp->gr[r].byte.h : read_handlers[r]())
#define REG_WRITE(r,d) { \
  int r1 = r; \
  if (r1 >= 4) write_handlers[r1](d); \
  else if (r1 > 0) ssp->gr[r1].byte.h = d; \
}

/* flags */
#define SSP_FLAG_L (1<<0xc)
#define SSP_FLAG_Z (1<<0xd)
#define SSP_FLAG_V (1<<0xe)
#define SSP_FLAG_N (1<<0xf)

/* update ZN according to 32bit ACC. */
#define UPD_ACC_ZN \
  rST &= ~(SSP_FLAG_Z|SSP_FLAG_N); \
  if (!rA32) rST |= SSP_FLAG_Z; \
  else rST |= (rA32>>16)&SSP_FLAG_N;

/* it seems SVP code never checks for L and OV, so we leave them out. */
/* rST |= (t>>4)&SSP_FLAG_L; */
#define UPD_LZVN \
  rST &= ~(SSP_FLAG_L|SSP_FLAG_Z|SSP_FLAG_V|SSP_FLAG_N); \
  if (!rA32) rST |= SSP_FLAG_Z; \
  else rST |= (rA32>>16)&SSP_FLAG_N;

/* standard cond processing. */
/* again, only Z and N is checked, as SVP doesn't seem to use any other conds. */
#define COND_CHECK \
  switch (op&0xf0) { \
    case 0x00: cond = 1; break; /* always true */ \
    case 0x50: cond = !((rST ^ (op<<5)) & SSP_FLAG_Z); break; /* Z matches f(?) bit */ \
    case 0x70: cond = !((rST ^ (op<<7)) & SSP_FLAG_N); break; /* N matches f(?) bit */ \
    default: break;  \
  }

/* ops with accumulator. */
/* how is low word really affected by these? */
/* nearly sure 'ld A' doesn't affect flags */
#define OP_LDA(x) \
  rA = x

#define OP_LDA32(x) \
  rA32 = x

#define OP_SUBA(x) { \
  rA32 -= (x) << 16; \
  UPD_LZVN \
}

#define OP_SUBA32(x) { \
  rA32 -= (x); \
  UPD_LZVN \
}

#define OP_CMPA(x) { \
  u32 t = rA32 - ((x) << 16); \
  rST &= ~(SSP_FLAG_L|SSP_FLAG_Z|SSP_FLAG_V|SSP_FLAG_N); \
  if (!t) rST |= SSP_FLAG_Z; \
  else    rST |= (t>>16)&SSP_FLAG_N; \
}

#define OP_CMPA32(x) { \
  u32 t = rA32 - (x); \
  rST &= ~(SSP_FLAG_L|SSP_FLAG_Z|SSP_FLAG_V|SSP_FLAG_N); \
  if (!t) rST |= SSP_FLAG_Z; \
  else    rST |= (t>>16)&SSP_FLAG_N; \
}

#define OP_ADDA(x) { \
  rA32 += (x) << 16; \
  UPD_LZVN \
}

#define OP_ADDA32(x) { \
  rA32 += (x); \
  UPD_LZVN \
}

#define OP_ANDA(x) \
  rA32 &= (x) << 16; \
  UPD_ACC_ZN

#define OP_ANDA32(x) \
  rA32 &= (x); \
  UPD_ACC_ZN

#define OP_ORA(x) \
  rA32 |= (x) << 16; \
  UPD_ACC_ZN

#define OP_ORA32(x) \
  rA32 |= (x); \
  UPD_ACC_ZN

#define OP_EORA(x) \
  rA32 ^= (x) << 16; \
  UPD_ACC_ZN

#define OP_EORA32(x) \
  rA32 ^= (x); \
  UPD_ACC_ZN


#define OP_CHECK32(OP) { \
  if ((op & 0x0f) == SSP_P) { /* A <- P */ \
    read_P(); /* update P */ \
    OP(rP.v); \
    break; \
  } \
  if ((op & 0x0f) == SSP_A) { /* A <- A */ \
    OP(rA32); \
    break; \
  } \
}


static ssp1601_t *ssp = NULL;
static unsigned short *PC;
static int g_cycles;

#ifdef USE_DEBUGGER
static int running = 0;
static int last_iram = 0;
#endif

/* ----------------------------------------------------- */
/* register i/o handlers */

/* 0-4, 13 */
static u32 read_unknown(void)
{
#ifdef LOG_SVP
  elprintf(EL_ANOMALY|EL_SVP, "ssp FIXME: unknown read @ %04x", GET_PPC_OFFS());
#endif
  return 0;
}

static void write_unknown(u32 d)
{
#ifdef LOG_SVP
  elprintf(EL_ANOMALY|EL_SVP, "ssp FIXME: unknown write @ %04x", GET_PPC_OFFS());
#endif
}

/* 4 */
static void write_ST(u32 d)
{
  /* if ((rST ^ d) & 0x0007) elprintf(EL_SVP, "ssp RPL %i -> %i @ %04x", rST&7, d&7, GET_PPC_OFFS()); */
#ifdef LOG_SVP
  if ((rST ^ d) & 0x0f98) elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME ST %04x -> %04x @ %04x", rST, d, GET_PPC_OFFS());
#endif
  rST = d;
}

/* 5 */
static u32 read_STACK(void)
{
  --rSTACK;
  if ((short)rSTACK < 0) {
    rSTACK = 5;
#ifdef LOG_SVP
    elprintf(EL_ANOMALY|EL_SVP, "ssp FIXME: stack underflow! (%i) @ %04x", rSTACK, GET_PPC_OFFS());
#endif
  }
  return ssp->stack[rSTACK];
}

static void write_STACK(u32 d)
{
  if (rSTACK >= 6) {
#ifdef LOG_SVP
    elprintf(EL_ANOMALY|EL_SVP, "ssp FIXME: stack overflow! (%i) @ %04x", rSTACK, GET_PPC_OFFS());
#endif
  rSTACK = 0;
  }
  ssp->stack[rSTACK++] = d;
}

/* 6 */
static u32 read_PC(void)
{
  /* g_cycles--; */
  return GET_PC();
}

static void write_PC(u32 d)
{
  SET_PC(d);
  g_cycles--;
}

/* 7 */
static u32 read_P(void)
{
  int m1 = (signed short)rX;
  int m2 = (signed short)rY;
  rP.v = (m1 * m2 * 2);
  return rP.byte.h;
}

/* ----------------------------------------------------- */

static int get_inc(int mode)
{
  int inc = (mode >> 11) & 7;
  if (inc != 0) {
    if (inc != 7) inc--;
    /* inc = (1<<16) << inc; */
    inc = 1 << inc; /* 0 1 2 4 8 16 32 128 */
    if (mode & 0x8000) inc = -inc; /* decrement mode */
  }
  return inc;
}

#define overwite_write(dst, d) \
{ \
  if (d & 0xf000) { dst &= ~0xf000; dst |= d & 0xf000; } \
  if (d & 0x0f00) { dst &= ~0x0f00; dst |= d & 0x0f00; } \
  if (d & 0x00f0) { dst &= ~0x00f0; dst |= d & 0x00f0; } \
  if (d & 0x000f) { dst &= ~0x000f; dst |= d & 0x000f; } \
}

static u32 pm_io(int reg, int write, u32 d)
{
  if (ssp->emu_status & SSP_PMC_SET)
  {
    /* this MUST be blind r or w */
    if ((*(PC-1) & 0xff0f) && (*(PC-1) & 0xfff0)) {
#ifdef LOG_SVP
      elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: tried to set PM%i (%c) with non-blind i/o %08x @ %04x",
        reg, write ? 'w' : 'r', rPMC.v, GET_PPC_OFFS());
#endif
      ssp->emu_status &= ~SSP_PMC_SET;
      return 0;
    }
#ifdef LOG_SVP
    elprintf(EL_SVP, "PM%i (%c) set to %08x @ %04x", reg, write ? 'w' : 'r', rPMC.v, GET_PPC_OFFS());
#endif
    ssp->pmac[write][reg] = rPMC.v;
    ssp->emu_status &= ~SSP_PMC_SET;
#ifdef LOG_SVP
    if ((rPMC.v & 0x7f) == 0x1c && (rPMC.v & 0x7fff0000) == 0) {
      elprintf(EL_SVP, "ssp IRAM copy from %06x", (ssp->mem.bank.RAM1[0]-1)<<1);
#ifdef USE_DEBUGGER
      last_iram = (ssp->mem.bank.RAM1[0]-1)<<1;
#endif
    }
#endif
    return 0;
  }

  /* just in case */
  if (ssp->emu_status & SSP_PMC_HAVE_ADDR) {
#ifdef LOG_SVP
    elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: PM%i (%c) with only addr set @ %04x",
      reg, write ? 'w' : 'r', GET_PPC_OFFS());
#endif
    ssp->emu_status &= ~SSP_PMC_HAVE_ADDR;
  }

  if (reg == 4 || (rST & 0x60))
  {
#ifdef LOG_SVP
    #define CADDR ((((mode<<16)&0x7f0000)|addr)<<1)
#endif
    unsigned short *dram = (unsigned short *)svp->dram;
    if (write)
    {
      /*int mode = ssp->pmac_write[reg]&0xffff;
      int addr = ssp->pmac_write[reg]>>16;*/
      int addr = ssp->pmac[1][reg]&0xffff;
      int mode = ssp->pmac[1][reg]>>16;
#ifdef LOG_SVP
      if ((mode & 0xb800) == 0xb800)
        elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: mode %04x", mode);
#endif
      if ((mode & 0x43ff) == 0x0018) /* DRAM */
      {
        int inc = get_inc(mode);
#ifdef LOG_SVP
        elprintf(EL_SVP, "ssp PM%i DRAM w [%06x] %04x (inc %i, ovrw %i)",
          reg, CADDR, d, inc >> 16, (mode>>10)&1);
#endif
        if (mode & 0x0400) {
               overwite_write(dram[addr], d);
        } else dram[addr] = d;
        ssp->pmac[1][reg] += inc;
      }
      else if ((mode & 0xfbff) == 0x4018) /* DRAM, cell inc */
      {
#ifdef LOG_SVP
        elprintf(EL_SVP, "ssp PM%i DRAM w [%06x] %04x (cell inc, ovrw %i) @ %04x",
          reg, CADDR, d, (mode>>10)&1, GET_PPC_OFFS());
#endif
        if (mode & 0x0400) {
               overwite_write(dram[addr], d);
        } else dram[addr] = d;
        /* ssp->pmac_write[reg] += (addr&1) ? (31<<16) : (1<<16); */
        ssp->pmac[1][reg] += (addr&1) ? 31 : 1;
      }
      else if ((mode & 0x47ff) == 0x001c) /* IRAM */
      {
        int inc = get_inc(mode);
#ifdef LOG_SVP
        if ((addr&0xfc00) != 0x8000)
          elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: invalid IRAM addr: %04x", addr<<1);
        elprintf(EL_SVP, "ssp IRAM w [%06x] %04x (inc %i)", (addr<<1)&0x7ff, d, inc >> 16);
#endif
        ((unsigned short *)svp->iram_rom)[addr&0x3ff] = d;
        ssp->pmac[1][reg] += inc;
      }
#ifdef LOG_SVP
      else
      {
        elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: PM%i unhandled write mode %04x, [%06x] %04x @ %04x",
            reg, mode, CADDR, d, GET_PPC_OFFS());
      }
#endif
    }
    else
    {
      /*int mode = ssp->pmac_read[reg]&0xffff;
      int addr = ssp->pmac_read[reg]>>16;*/
      int addr = ssp->pmac[0][reg]&0xffff;
      int mode = ssp->pmac[0][reg]>>16;

      if      ((mode & 0xfff0) == 0x0800) /* ROM, inc 1, verified to be correct */
      {
#ifdef LOG_SVP
        elprintf(EL_SVP, "ssp ROM  r [%06x] %04x", CADDR,
          ((unsigned short *)cart.rom)[addr|((mode&0xf)<<16)]);
#endif
        /*if ((signed int)ssp->pmac_read[reg] >> 16 == -1) ssp->pmac_read[reg]++;
        ssp->pmac_read[reg] += 1<<16;*/
        if ((signed int)(ssp->pmac[0][reg] & 0xffff) == -1) ssp->pmac[0][reg] += 1<<16;
        ssp->pmac[0][reg] ++;
        
        d = ((unsigned short *)cart.rom)[addr|((mode&0xf)<<16)];
      }
      else if ((mode & 0x47ff) == 0x0018) /* DRAM */
      {
        int inc = get_inc(mode);
#ifdef LOG_SVP
        elprintf(EL_SVP, "ssp PM%i DRAM r [%06x] %04x (inc %i)", reg, CADDR, dram[addr], inc >> 16);
#endif
        d = dram[addr];
        ssp->pmac[0][reg] += inc;
      }
      else
      {
#ifdef LOG_SVP
        elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: PM%i unhandled read  mode %04x, [%06x] @ %04x",
            reg, mode, CADDR, GET_PPC_OFFS());
#endif
        d = 0;
      }
    }

    /* PMC value corresponds to last PMR accessed (not sure). */
    rPMC.v = ssp->pmac[write][reg];

    return d;
  }

  return (u32)-1;
}

/* 8 */
static u32 read_PM0(void)
{
  u32 d = pm_io(0, 0, 0);
  if (d != (u32)-1) return d;
#ifdef LOG_SVP
  elprintf(EL_SVP, "PM0 raw r %04x @ %04x", rPM0, GET_PPC_OFFS());
#endif
  d = rPM0;
  if (!(d & 2) && (GET_PPC_OFFS() == 0x800 || GET_PPC_OFFS() == 0x1851E)) {
    ssp->emu_status |= SSP_WAIT_PM0;
#ifdef LOG_SVP
    elprintf(EL_SVP, "det TIGHT loop: PM0");
#endif
  }
  rPM0 &= ~2; /* ? */
  return d;
}

static void write_PM0(u32 d)
{
  u32 r = pm_io(0, 1, d);
  if (r != (u32)-1) return;
#ifdef LOG_SVP
  elprintf(EL_SVP, "PM0 raw w %04x @ %04x", d, GET_PPC_OFFS());
#endif
  rPM0 = d;
}

/* 9 */
static u32 read_PM1(void)
{
  u32 d = pm_io(1, 0, 0);
  if (d != (u32)-1) return d;
  /* can be removed? */
#ifdef LOG_SVP
  elprintf(EL_SVP|EL_ANOMALY, "PM1 raw r %04x @ %04x", rPM1, GET_PPC_OFFS());
#endif
  return rPM1;
}

static void write_PM1(u32 d)
{
  u32 r = pm_io(1, 1, d);
  if (r != (u32)-1) return;
  /* can be removed? */
#ifdef LOG_SVP
  elprintf(EL_SVP|EL_ANOMALY, "PM1 raw w %04x @ %04x", d, GET_PPC_OFFS());
#endif
  rPM1 = d;
}

/* 10 */
static u32 read_PM2(void)
{
  u32 d = pm_io(2, 0, 0);
  if (d != (u32)-1) return d;
  /* can be removed? */
#ifdef LOG_SVP
  elprintf(EL_SVP|EL_ANOMALY, "PM2 raw r %04x @ %04x", rPM2, GET_PPC_OFFS());
#endif
  return rPM2;
}

static void write_PM2(u32 d)
{
  u32 r = pm_io(2, 1, d);
  if (r != (u32)-1) return;
  /* can be removed? */
#ifdef LOG_SVP
  elprintf(EL_SVP|EL_ANOMALY, "PM2 raw w %04x @ %04x", d, GET_PPC_OFFS());
#endif
  rPM2 = d;
}

/* 11 */
static u32 read_XST(void)
{
  /* can be removed? */
  u32 d = pm_io(3, 0, 0);
  if (d != (u32)-1) return d;
#ifdef LOG_SVP
  elprintf(EL_SVP, "XST raw r %04x @ %04x", rXST, GET_PPC_OFFS());
#endif
  return rXST;
}

static void write_XST(u32 d)
{
  /* can be removed? */
  u32 r = pm_io(3, 1, d);
  if (r != (u32)-1) return;
#ifdef LOG_SVP
  elprintf(EL_SVP, "XST raw w %04x @ %04x", d, GET_PPC_OFFS());
#endif
  rPM0 |= 1;
  rXST = d;
}

/* 12 */
static u32 read_PM4(void)
{
  u32 d = pm_io(4, 0, 0);
  if (d == 0) {
    switch (GET_PPC_OFFS()) {
      case 0x0854:
        ssp->emu_status |= SSP_WAIT_30FE08;
#ifdef LOG_SVP
        elprintf(EL_SVP, "det TIGHT loop: [30fe08]");
#endif
        break;
      case 0x4f12:
        ssp->emu_status |= SSP_WAIT_30FE06;
#ifdef LOG_SVP
        elprintf(EL_SVP, "det TIGHT loop: [30fe06]");
#endif
        break;
    }
  }
  if (d != (u32)-1) return d;
  /* can be removed? */
#ifdef LOG_SVP
  elprintf(EL_SVP|EL_ANOMALY, "PM4 raw r %04x @ %04x", rPM4, GET_PPC_OFFS());
#endif
  return rPM4;
}

static void write_PM4(u32 d)
{
  u32 r = pm_io(4, 1, d);
  if (r != (u32)-1) return;
  /* can be removed? */
#ifdef LOG_SVP
  elprintf(EL_SVP|EL_ANOMALY, "PM4 raw w %04x @ %04x", d, GET_PPC_OFFS());
#endif
  rPM4 = d;
}

/* 14 */
static u32 read_PMC(void)
{
#ifdef LOG_SVP
  elprintf(EL_SVP, "PMC r a %04x (st %c) @ %04x", rPMC.byte.h,
    (ssp->emu_status & SSP_PMC_HAVE_ADDR) ? 'm' : 'a', GET_PPC_OFFS());
#endif
  if (ssp->emu_status & SSP_PMC_HAVE_ADDR) {
    /* if (ssp->emu_status & SSP_PMC_SET) */
    /*  elprintf(EL_ANOMALY|EL_SVP, "prev PMC not used @ %04x", GET_PPC_OFFS()); */
    ssp->emu_status |= SSP_PMC_SET;
    ssp->emu_status &= ~SSP_PMC_HAVE_ADDR;
    /* return ((rPMC.h << 4) & 0xfff0) | ((rPMC.h >> 4) & 0xf); */
    return ((rPMC.byte.l << 4) & 0xfff0) | ((rPMC.byte.l >> 4) & 0xf);
  } else {
    ssp->emu_status |= SSP_PMC_HAVE_ADDR;
    /* return rPMC.h; */
    return rPMC.byte.l;
  }
}

static void write_PMC(u32 d)
{
  if (ssp->emu_status & SSP_PMC_HAVE_ADDR) {
    /* if (ssp->emu_status & SSP_PMC_SET) */
    /*  elprintf(EL_ANOMALY|EL_SVP, "prev PMC not used @ %04x", GET_PPC_OFFS()); */
    ssp->emu_status |= SSP_PMC_SET;
    ssp->emu_status &= ~SSP_PMC_HAVE_ADDR;
    /* rPMC.l = d; */
    rPMC.byte.h = d;
#ifdef LOG_SVP
    elprintf(EL_SVP, "PMC w m %04x @ %04x", rPMC.byte.l, GET_PPC_OFFS());
#endif
  } else {
    ssp->emu_status |= SSP_PMC_HAVE_ADDR;
    /* rPMC.h = d; */
    rPMC.byte.l = d;
#ifdef LOG_SVP
    elprintf(EL_SVP, "PMC w a %04x @ %04x", rPMC.byte.h, GET_PPC_OFFS());
#endif
  }
}

/* 15 */
static u32 read_AL(void)
{
  if (*(PC-1) == 0x000f) {
#ifdef LOG_SVP
    elprintf(EL_SVP, "ssp dummy PM assign %08x @ %04x", rPMC.v, GET_PPC_OFFS());
#endif
    ssp->emu_status &= ~(SSP_PMC_SET|SSP_PMC_HAVE_ADDR); /* ? */
  }
  return rAL;
}

static void write_AL(u32 d)
{
  rAL = d;
}


typedef u32 (*read_func_t)(void);
typedef void (*write_func_t)(u32 d);

static read_func_t read_handlers[16] =
{
  read_unknown, read_unknown, read_unknown, read_unknown, /* -, X, Y, A */
  read_unknown,  /* 4 ST */
  read_STACK,
  read_PC,
  read_P,
  read_PM0,  /* 8 */
  read_PM1,
  read_PM2,
  read_XST,
  read_PM4,  /* 12 */
  read_unknown,  /* 13 gr13 */
  read_PMC,
  read_AL
};

static write_func_t write_handlers[16] =
{
  write_unknown, write_unknown, write_unknown, write_unknown, /* -, X, Y, A */
/*  write_unknown, */ /* 4 ST */
  write_ST,  /* 4 ST (debug hook) */
  write_STACK,
  write_PC,
  write_unknown,  /* 7 P */
  write_PM0,  /* 8 */
  write_PM1,
  write_PM2,
  write_XST,
  write_PM4,  /* 12 */
  write_unknown,  /* 13 gr13 */
  write_PMC,
  write_AL
};

/* ----------------------------------------------------- */
/* pointer register handlers */

#define ptr1_read(op) ptr1_read_(op&3,(op>>6)&4,(op<<1)&0x18)

static u32 ptr1_read_(int ri, int isj2, int modi3)
{
  /* int t = (op&3) | ((op>>6)&4) | ((op<<1)&0x18); */
  u32 mask, add = 0, t = ri | isj2 | modi3;
  unsigned char *rp = NULL;
  switch (t)
  {
    /* mod=0 (00) */
    case 0x00:
    case 0x01:
    case 0x02: return ssp->mem.bank.RAM0[ssp->ptr.bank.r0[t&3]];
    case 0x03: return ssp->mem.bank.RAM0[0];
    case 0x04:
    case 0x05:
    case 0x06: return ssp->mem.bank.RAM1[ssp->ptr.bank.r1[t&3]];
    case 0x07: return ssp->mem.bank.RAM1[0];
    /* mod=1 (01), "+!" */
    case 0x08:
    case 0x09:
    case 0x0a: return ssp->mem.bank.RAM0[ssp->ptr.bank.r0[t&3]++];
    case 0x0b: return ssp->mem.bank.RAM0[1];
    case 0x0c:
    case 0x0d:
    case 0x0e: return ssp->mem.bank.RAM1[ssp->ptr.bank.r1[t&3]++];
    case 0x0f: return ssp->mem.bank.RAM1[1];
    /* mod=2 (10), "-" */
    case 0x10:
    case 0x11:
    case 0x12: rp = &ssp->ptr.bank.r0[t&3]; t = ssp->mem.bank.RAM0[*rp];
               if (!(rST&7)) { (*rp)--; return t; }
               add = -1; goto modulo;
    case 0x13: return ssp->mem.bank.RAM0[2];
    case 0x14:
    case 0x15:
    case 0x16: rp = &ssp->ptr.bank.r1[t&3]; t = ssp->mem.bank.RAM1[*rp];
               if (!(rST&7)) { (*rp)--; return t; }
               add = -1; goto modulo;
    case 0x17: return ssp->mem.bank.RAM1[2];
    /* mod=3 (11), "+" */
    case 0x18:
    case 0x19:
    case 0x1a: rp = &ssp->ptr.bank.r0[t&3]; t = ssp->mem.bank.RAM0[*rp];
               if (!(rST&7)) { (*rp)++; return t; }
               add = 1; goto modulo;
    case 0x1b: return ssp->mem.bank.RAM0[3];
    case 0x1c:
    case 0x1d:
    case 0x1e: rp = &ssp->ptr.bank.r1[t&3]; t = ssp->mem.bank.RAM1[*rp];
               if (!(rST&7)) { (*rp)++; return t; }
               add = 1; goto modulo;
    case 0x1f: return ssp->mem.bank.RAM1[3];
  }

  return 0;

modulo:
  mask = (1 << (rST&7)) - 1;
  *rp = (*rp & ~mask) | ((*rp + add) & mask);
  return t;
}

static void ptr1_write(int op, u32 d)
{
  int t = (op&3) | ((op>>6)&4) | ((op<<1)&0x18);
  switch (t)
  {
    /* mod=0 (00) */
    case 0x00:
    case 0x01:
    case 0x02: ssp->mem.bank.RAM0[ssp->ptr.bank.r0[t&3]] = d; return;
    case 0x03: ssp->mem.bank.RAM0[0] = d; return;
    case 0x04:
    case 0x05:
    case 0x06: ssp->mem.bank.RAM1[ssp->ptr.bank.r1[t&3]] = d; return;
    case 0x07: ssp->mem.bank.RAM1[0] = d; return;
    /* mod=1 (01), "+!" */
    /* mod=3,      "+" */
    case 0x08:
    case 0x18:
    case 0x09:
    case 0x19:
    case 0x0a:
    case 0x1a: ssp->mem.bank.RAM0[ssp->ptr.bank.r0[t&3]++] = d; return;
    case 0x0b: ssp->mem.bank.RAM0[1] = d; return;
    case 0x0c:
    case 0x1c:
    case 0x0d:
    case 0x1d:
    case 0x0e:
    case 0x1e: ssp->mem.bank.RAM1[ssp->ptr.bank.r1[t&3]++] = d; return;
    case 0x0f: ssp->mem.bank.RAM1[1] = d; return;
    /* mod=2 (10), "-" */
    case 0x10:
    case 0x11:
    case 0x12: ssp->mem.bank.RAM0[ssp->ptr.bank.r0[t&3]--] = d; return;
    case 0x13: ssp->mem.bank.RAM0[2] = d; return;
    case 0x14:
    case 0x15:
    case 0x16: ssp->mem.bank.RAM1[ssp->ptr.bank.r1[t&3]--] = d; return;
    case 0x17: ssp->mem.bank.RAM1[2] = d; return;
    /* mod=3 (11) */
    case 0x1b: ssp->mem.bank.RAM0[3] = d; return;
    case 0x1f: ssp->mem.bank.RAM1[3] = d; return;
  }
}

static u32 ptr2_read(int op)
{
  int mv = 0, t = (op&3) | ((op>>6)&4) | ((op<<1)&0x18);
  switch (t)
  {
    /* mod=0 (00) */
    case 0x00:
    case 0x01:
    case 0x02: mv = ssp->mem.bank.RAM0[ssp->ptr.bank.r0[t&3]]++; break;
    case 0x03: mv = ssp->mem.bank.RAM0[0]++; break;
    case 0x04:
    case 0x05:
    case 0x06: mv = ssp->mem.bank.RAM1[ssp->ptr.bank.r1[t&3]]++; break;
    case 0x07: mv = ssp->mem.bank.RAM1[0]++; break;
    /* mod=1 (01) */
    case 0x0b: mv = ssp->mem.bank.RAM0[1]++; break;
    case 0x0f: mv = ssp->mem.bank.RAM1[1]++; break;
    /* mod=2 (10) */
    case 0x13: mv = ssp->mem.bank.RAM0[2]++; break;
    case 0x17: mv = ssp->mem.bank.RAM1[2]++; break;
    /* mod=3 (11) */
    case 0x1b: mv = ssp->mem.bank.RAM0[3]++; break;
    case 0x1f: mv = ssp->mem.bank.RAM1[3]++; break;
    default:
#ifdef LOG_SVP
      elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: invalid mod in ((rX))? @ %04x", GET_PPC_OFFS());
#endif
      return 0;
  }

  return ((unsigned short *)svp->iram_rom)[mv];
}


/* ----------------------------------------------------- */

void ssp1601_reset(ssp1601_t *l_ssp)
{
  ssp = l_ssp;
  ssp->emu_status = 0;
  ssp->gr[SSP_GR0].v = 0xffff0000;
  rPC = 0x400;
  rSTACK = 0; /* ? using ascending stack */
  rST = 0;
}


#ifdef USE_DEBUGGER
static void debug_dump(void)
{
  printf("GR0:   %04x    X: %04x    Y: %04x  A: %08x\n", ssp->gr[SSP_GR0].byte.h, rX, rY, ssp->gr[SSP_A].v);
  printf("PC:    %04x  (%04x)                P: %08x\n", GET_PC(), GET_PC() << 1, ssp->gr[SSP_P].v);
  printf("PM0:   %04x  PM1: %04x  PM2: %04x\n", rPM0, rPM1, rPM2);
  printf("XST:   %04x  PM4: %04x  PMC: %08x\n", rXST, rPM4, ssp->gr[SSP_PMC].v);
  printf(" ST:   %04x  %c%c%c%c,  GP0_0 %i,  GP0_1 %i\n", rST, rST&SSP_FLAG_N?'N':'n', rST&SSP_FLAG_V?'V':'v',
    rST&SSP_FLAG_Z?'Z':'z', rST&SSP_FLAG_L?'L':'l', (rST>>5)&1, (rST>>6)&1);
  printf("STACK: %i %04x %04x %04x %04x %04x %04x\n", rSTACK, ssp->stack[0], ssp->stack[1],
    ssp->stack[2], ssp->stack[3], ssp->stack[4], ssp->stack[5]);
  printf("r0-r2: %02x %02x %02x  r4-r6: %02x %02x %02x\n", rIJ[0], rIJ[1], rIJ[2], rIJ[4], rIJ[5], rIJ[6]);
  elprintf(EL_SVP, "cycles: %i, emu_status: %x", g_cycles, ssp->emu_status);
}

static void debug_dump_mem(void)
{
  int h, i;
  printf("RAM0\n");
  for (h = 0; h < 32; h++)
  {
    if (h == 16) printf("RAM1\n");
    printf("%03x:", h*16);
    for (i = 0; i < 16; i++)
      printf(" %04x", ssp->mem.RAM[h*16+i]);
    printf("\n");
  }
}

static void debug_dump2file(const char *fname, void *mem, int len)
{
  FILE *f = fopen(fname, "wb");
  unsigned short *p = mem;
  int i;
  if (f) {
    for (i = 0; i < len/2; i++) p[i] = (p[i]<<8) | (p[i]>>8);
    fwrite(mem, 1, len, f);
    fclose(f);
    for (i = 0; i < len/2; i++) p[i] = (p[i]<<8) | (p[i]>>8);
    printf("dumped to %s\n", fname);
  }
  else
    printf("dump failed\n");
}

static int bpts[10] = { 0, };

static void debug(unsigned int pc, unsigned int op)
{
  static char buffo[64] = {0,};
  char buff[64] = {0,};
  int i;

  if (running) {
    for (i = 0; i < 10; i++)
      if (pc != 0 && bpts[i] == pc) {
        printf("breakpoint %i\n", i);
        running = 0;
        break;
      }
  }
  if (running) return;

  printf("%04x (%02x) @ %04x\n", op, op >> 9, pc<<1);

  while (1)
  {
    printf("dbg> ");
    fflush(stdout);
    fgets(buff, sizeof(buff), stdin);
    if (buff[0] == '\n') strcpy(buff, buffo);
    else strcpy(buffo, buff);

    switch (buff[0]) {
      case   0: exit(0);
      case 'c':
      case 'r': running = 1; return;
      case 's':
      case 'n': return;
      case 'x': debug_dump(); break;
      case 'm': debug_dump_mem(); break;
      case 'b': {
        char *baddr = buff + 2;
        i = 0;
        if (buff[3] == ' ') { i = buff[2] - '0'; baddr = buff + 4; }
        bpts[i] = strtol(baddr, NULL, 16) >> 1;
        printf("breakpoint %i set @ %04x\n", i, bpts[i]<<1);
        break;
      }
      case 'd':
        sprintf(buff, "iramrom_%04x.bin", last_iram);
        debug_dump2file(buff, svp->iram_rom, sizeof(svp->iram_rom));
        debug_dump2file("dram.bin", svp->dram, sizeof(svp->dram));
        break;
      default:  printf("unknown command\n"); break;
    }
  }
}
#endif /* USE_DEBUGGER */


void ssp1601_run(int cycles)
{
  SET_PC(rPC);
  g_cycles = cycles;

  do
  {
    int op;
    u32 tmpv;

    op = *PC++;
#ifdef USE_DEBUGGER
    debug(GET_PC()-1, op);
#endif
    switch (op >> 9)
    {
      /* ld d, s */
      case 0x00:
        if (op == 0) break; /* nop */
        if (op == ((SSP_A<<4)|SSP_P)) { /* A <- P */
          /* not sure. MAME claims that only hi word is transfered. */
          read_P(); /* update P */
          rA32 = rP.v;
        }
        else
        {
          tmpv = REG_READ(op & 0x0f);
          REG_WRITE((op & 0xf0) >> 4, tmpv);
        }
        break;

      /* ld d, (ri) */
      case 0x01: tmpv = ptr1_read(op); REG_WRITE((op & 0xf0) >> 4, tmpv); break;

      /* ld (ri), s */
      case 0x02: tmpv = REG_READ((op & 0xf0) >> 4); ptr1_write(op, tmpv); break;

      /* ldi d, imm */
      case 0x04: tmpv = *PC++; REG_WRITE((op & 0xf0) >> 4, tmpv); break;

      /* ld d, ((ri)) */
      case 0x05: tmpv = ptr2_read(op); REG_WRITE((op & 0xf0) >> 4, tmpv); break;

      /* ldi (ri), imm */
      case 0x06: tmpv = *PC++; ptr1_write(op, tmpv); break;

      /* ld adr, a */
      case 0x07: ssp->mem.RAM[op & 0x1ff] = rA; break;

      /* ld d, ri */
      case 0x09: tmpv = rIJ[(op&3)|((op>>6)&4)]; REG_WRITE((op & 0xf0) >> 4, tmpv); break;

      /* ld ri, s */
      case 0x0a: rIJ[(op&3)|((op>>6)&4)] = REG_READ((op & 0xf0) >> 4); break;

      /* ldi ri, simm */
      case 0x0c:
      case 0x0d:
      case 0x0e:
      case 0x0f: rIJ[(op>>8)&7] = op; break;

      /* call cond, addr */
      case 0x24: {
        int cond = 0;
        COND_CHECK
        if (cond) { int new_PC = *PC++; write_STACK(GET_PC()); write_PC(new_PC); }
        else PC++;
        break;
      }

      /* ld d, (a) */
      case 0x25: tmpv = ((unsigned short *)svp->iram_rom)[rA]; REG_WRITE((op & 0xf0) >> 4, tmpv); break;

      /* bra cond, addr */
      case 0x26: {
        int cond = 0;
        COND_CHECK
        if (cond) { int new_PC = *PC++; write_PC(new_PC); }
        else PC++;
        break;
      }

      /* mod cond, op */
      case 0x48: {
        int cond = 0;
        COND_CHECK
        if (cond) {
          switch (op & 7) {
            case 2: rA32 = (signed int)rA32 >> 1; break; /* shr (arithmetic) */
            case 3: rA32 <<= 1; break; /* shl */
            case 6: rA32 = -(signed int)rA32; break; /* neg */
            case 7: if ((int)rA32 < 0) rA32 = -(signed int)rA32; break; /* abs */
            default:
#ifdef LOG_SVP
              elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: unhandled mod %i @ %04x",
                op&7, GET_PPC_OFFS());
#endif
              break;
          }
          UPD_ACC_ZN /* ? */
        }
        break;
      }

      /* mpys? */
      case 0x1b:
#ifdef LOG_SVP
        if (!(op&0x100)) elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: no b bit @ %04x", GET_PPC_OFFS());
#endif
        read_P(); /* update P */
        rA32 -= rP.v;  /* maybe only upper word? */
        UPD_ACC_ZN      /* there checking flags after this */
        rX = ptr1_read_(op&3, 0, (op<<1)&0x18); /* ri (maybe rj?) */
        rY = ptr1_read_((op>>4)&3, 4, (op>>3)&0x18); /* rj */
        break;

      /* mpya (rj), (ri), b */
      case 0x4b:
#ifdef LOG_SVP
        if (!(op&0x100)) elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: no b bit @ %04x", GET_PPC_OFFS());
#endif
        read_P(); /* update P */
        rA32 += rP.v; /* confirmed to be 32bit */
        UPD_ACC_ZN /* ? */
        rX = ptr1_read_(op&3, 0, (op<<1)&0x18); /* ri (maybe rj?) */
        rY = ptr1_read_((op>>4)&3, 4, (op>>3)&0x18); /* rj */
        break;

      /* mld (rj), (ri), b */
      case 0x5b:
#ifdef LOG_SVP
        if (!(op&0x100)) elprintf(EL_SVP|EL_ANOMALY, "ssp FIXME: no b bit @ %04x", GET_PPC_OFFS());
#endif
        rA32 = 0;
        rST &= 0x0fff; /* ? */
        rX = ptr1_read_(op&3, 0, (op<<1)&0x18); /* ri (maybe rj?) */
        rY = ptr1_read_((op>>4)&3, 4, (op>>3)&0x18); /* rj */
        break;

      /* OP a, s */
      case 0x10: OP_CHECK32(OP_SUBA32); tmpv = REG_READ(op & 0x0f); OP_SUBA(tmpv); break;
      case 0x30: OP_CHECK32(OP_CMPA32); tmpv = REG_READ(op & 0x0f); OP_CMPA(tmpv); break;
      case 0x40: OP_CHECK32(OP_ADDA32); tmpv = REG_READ(op & 0x0f); OP_ADDA(tmpv); break;
      case 0x50: OP_CHECK32(OP_ANDA32); tmpv = REG_READ(op & 0x0f); OP_ANDA(tmpv); break;
      case 0x60: OP_CHECK32(OP_ORA32 ); tmpv = REG_READ(op & 0x0f); OP_ORA (tmpv); break;
      case 0x70: OP_CHECK32(OP_EORA32); tmpv = REG_READ(op & 0x0f); OP_EORA(tmpv); break;

      /* OP a, (ri) */
      case 0x11: tmpv = ptr1_read(op); OP_SUBA(tmpv); break;
      case 0x31: tmpv = ptr1_read(op); OP_CMPA(tmpv); break;
      case 0x41: tmpv = ptr1_read(op); OP_ADDA(tmpv); break;
      case 0x51: tmpv = ptr1_read(op); OP_ANDA(tmpv); break;
      case 0x61: tmpv = ptr1_read(op); OP_ORA (tmpv); break;
      case 0x71: tmpv = ptr1_read(op); OP_EORA(tmpv); break;

      /* OP a, adr */
      case 0x03: tmpv = ssp->mem.RAM[op & 0x1ff]; OP_LDA (tmpv); break;
      case 0x13: tmpv = ssp->mem.RAM[op & 0x1ff]; OP_SUBA(tmpv); break;
      case 0x33: tmpv = ssp->mem.RAM[op & 0x1ff]; OP_CMPA(tmpv); break;
      case 0x43: tmpv = ssp->mem.RAM[op & 0x1ff]; OP_ADDA(tmpv); break;
      case 0x53: tmpv = ssp->mem.RAM[op & 0x1ff]; OP_ANDA(tmpv); break;
      case 0x63: tmpv = ssp->mem.RAM[op & 0x1ff]; OP_ORA (tmpv); break;
      case 0x73: tmpv = ssp->mem.RAM[op & 0x1ff]; OP_EORA(tmpv); break;

      /* OP a, imm */
      case 0x14: tmpv = *PC++; OP_SUBA(tmpv); break;
      case 0x34: tmpv = *PC++; OP_CMPA(tmpv); break;
      case 0x44: tmpv = *PC++; OP_ADDA(tmpv); break;
      case 0x54: tmpv = *PC++; OP_ANDA(tmpv); break;
      case 0x64: tmpv = *PC++; OP_ORA (tmpv); break;
      case 0x74: tmpv = *PC++; OP_EORA(tmpv); break;

      /* OP a, ((ri)) */
      case 0x15: tmpv = ptr2_read(op); OP_SUBA(tmpv); break;
      case 0x35: tmpv = ptr2_read(op); OP_CMPA(tmpv); break;
      case 0x45: tmpv = ptr2_read(op); OP_ADDA(tmpv); break;
      case 0x55: tmpv = ptr2_read(op); OP_ANDA(tmpv); break;
      case 0x65: tmpv = ptr2_read(op); OP_ORA (tmpv); break;
      case 0x75: tmpv = ptr2_read(op); OP_EORA(tmpv); break;

      /* OP a, ri */
      case 0x19: tmpv = rIJ[IJind]; OP_SUBA(tmpv); break;
      case 0x39: tmpv = rIJ[IJind]; OP_CMPA(tmpv); break;
      case 0x49: tmpv = rIJ[IJind]; OP_ADDA(tmpv); break;
      case 0x59: tmpv = rIJ[IJind]; OP_ANDA(tmpv); break;
      case 0x69: tmpv = rIJ[IJind]; OP_ORA (tmpv); break;
      case 0x79: tmpv = rIJ[IJind]; OP_EORA(tmpv); break;

      /* OP simm */
      case 0x1c:
        OP_SUBA(op & 0xff);
#ifdef LOG_SVP
        if (op&0x100) elprintf(EL_SVP|EL_ANOMALY, "FIXME: simm with upper bit set");
#endif
        break;
      case 0x3c:
        OP_CMPA(op & 0xff); 
#ifdef LOG_SVP
        if (op&0x100) elprintf(EL_SVP|EL_ANOMALY, "FIXME: simm with upper bit set");
#endif
        break;
      case 0x4c:
        OP_ADDA(op & 0xff);
#ifdef LOG_SVP
        if (op&0x100) elprintf(EL_SVP|EL_ANOMALY, "FIXME: simm with upper bit set");
#endif
        break;
      /* MAME code only does LSB of top word, but this looks wrong to me. */
      case 0x5c:
        OP_ANDA(op & 0xff);
#ifdef LOG_SVP
        if (op&0x100) elprintf(EL_SVP|EL_ANOMALY, "FIXME: simm with upper bit set");
#endif
        break;
      case 0x6c:
        OP_ORA (op & 0xff);
#ifdef LOG_SVP
        if (op&0x100) elprintf(EL_SVP|EL_ANOMALY, "FIXME: simm with upper bit set");
#endif
        break;
      case 0x7c:
        OP_EORA(op & 0xff); 
#ifdef LOG_SVP
        if (op&0x100) elprintf(EL_SVP|EL_ANOMALY, "FIXME: simm with upper bit set");
#endif
        break;

      default:
#ifdef LOG_SVP
        elprintf(EL_ANOMALY|EL_SVP, "ssp FIXME unhandled op %04x @ %04x", op, GET_PPC_OFFS());
#endif
        break;
    }
  }
  while (--g_cycles > 0 && !(ssp->emu_status & SSP_WAIT_MASK));

  read_P(); /* update P */
  rPC = GET_PC();

#ifdef LOG_SVP
  if (ssp->gr[SSP_GR0].v != 0xffff0000)
    elprintf(EL_ANOMALY|EL_SVP, "ssp FIXME: REG 0 corruption! %08x", ssp->gr[SSP_GR0].v);
#endif
}