factor/vm/cpu-ppc.hpp

namespace factor {

#ifdef FACTOR_64
#define FACTOR_CPU_STRING "ppc.64"
#else
#define FACTOR_CPU_STRING "ppc.32"
#endif

#define CALLSTACK_BOTTOM(ctx) (ctx->callstack_seg->end - 32)

// In the instruction sequence:

// LOAD32 r3,...
// B blah

// the offset from the immediate operand to LOAD32 to the instruction after
// the branch is one instruction.
static const fixnum xt_tail_pic_offset = 4;

inline static void check_call_site(cell return_address) {
  uint32_t insn = *(uint32_t*)return_address;
  // Check that absolute bit is 0
  FACTOR_ASSERT((insn & 0x2) == 0x0);
  // Check that instruction is branch
  FACTOR_ASSERT((insn >> 26) == 0x12);
}

static const uint32_t b_mask = 0x3fffffc;

inline static void* get_call_target(cell return_address) {
  return_address -= 4;
  check_call_site(return_address);

  uint32_t insn = *(uint32_t*)return_address;
  uint32_t unsigned_addr = (insn & b_mask);
  int32_t signed_addr = (int32_t)(unsigned_addr << 6) >> 6;
  return (void*)(signed_addr + return_address);
}

inline static void set_call_target(cell return_address, cell target) {
  return_address -= 4;
  check_call_site(return_address);

  uint32_t insn = *(uint32_t*)return_address;

  fixnum relative_address = target - return_address;
  insn = ((insn & ~b_mask) | (relative_address & b_mask));
  *(uint32_t*)return_address = insn;

  // Flush the cache line containing the call we just patched
  __asm__ __volatile__("icbi 0, %0\n"
                       "sync\n" ::"r"(return_address)
                       :);
}

inline static bool tail_call_site_p(cell return_address) {
  return_address -= 4;
  uint32_t insn = *(uint32_t*)return_address;
  return (insn & 0x1) == 0;
}

inline static unsigned int fpu_status(unsigned int status) {
  unsigned int r = 0;

  if (status & 0x20000000)
    r |= FP_TRAP_INVALID_OPERATION;
  if (status & 0x10000000)
    r |= FP_TRAP_OVERFLOW;
  if (status & 0x08000000)
    r |= FP_TRAP_UNDERFLOW;
  if (status & 0x04000000)
    r |= FP_TRAP_ZERO_DIVIDE;
  if (status & 0x02000000)
    r |= FP_TRAP_INEXACT;

  return r;
}

// Defined in assembly
VM_C_API void flush_icache(cell start, cell len);

}