1 files changed, 741 insertions, 0 deletions

diff --git a/src/lj_cconv.c b/src/lj_cconv.c
new file mode 100644
index 00000000..f68f86a4
--- /dev/null
+++ b/src/lj_cconv.c
@@ -0,0 +1,741 @@
+/*
+** C type conversions.
+** Copyright (C) 2005-2010 Mike Pall. See Copyright Notice in luajit.h
+*/
+
+#include "lj_obj.h"
+
+#if LJ_HASFFI
+
+#include "lj_err.h"
+#include "lj_tab.h"
+#include "lj_ctype.h"
+#include "lj_cdata.h"
+#include "lj_cconv.h"
+
+/* -- Conversion errors --------------------------------------------------- */
+
+/* Bad conversion. */
+LJ_NORET static void cconv_err_conv(CTState *cts, CType *d, CType *s,
+                                    CTInfo flags)
+{
+  const char *dst = strdata(lj_ctype_repr(cts->L, ctype_typeid(cts, d), NULL));
+  const char *src;
+  if ((flags & CCF_FROMTV))
+    src = lj_obj_typename[1+(ctype_isnum(s->info) ? LUA_TNUMBER : LUA_TSTRING)];
+  else
+    src = strdata(lj_ctype_repr(cts->L, ctype_typeid(cts, s), NULL));
+  lj_err_callerv(cts->L, LJ_ERR_FFI_BADCONV, src, dst);
+}
+
+/* Bad conversion from TValue. */
+LJ_NORET static void cconv_err_convtv(CTState *cts, CType *d, TValue *o)
+{
+  const char *dst = strdata(lj_ctype_repr(cts->L, ctype_typeid(cts, d), NULL));
+  lj_err_callerv(cts->L, LJ_ERR_FFI_BADCONV, typename(o), dst);
+}
+
+/* Initializer overflow. */
+LJ_NORET static void cconv_err_initov(CTState *cts, CType *d)
+{
+  const char *dst = strdata(lj_ctype_repr(cts->L, ctype_typeid(cts, d), NULL));
+  lj_err_callerv(cts->L, LJ_ERR_FFI_INITOV, dst);
+}
+
+/* -- C type compatibility checks ----------------------------------------- */
+
+/* Get raw type and qualifiers for a child type. Resolves enums, too. */
+static CType *cconv_childqual(CTState *cts, CType *ct, CTInfo *qual)
+{
+  ct = ctype_child(cts, ct);
+  for (;;) {
+    if (ctype_isattrib(ct->info)) {
+      if (ctype_attrib(ct->info) == CTA_QUAL) *qual |= ct->size;
+    } else if (!ctype_isenum(ct->info)) {
+      break;
+    }
+    ct = ctype_child(cts, ct);
+  }
+  *qual |= (ct->info & CTF_QUAL);
+  return ct;
+}
+
+/* Check for compatible types when converting to a pointer.
+** Note: these checks are more relaxed than what C99 mandates.
+*/
+static int cconv_compatptr(CTState *cts, CType *d, CType *s, CTInfo flags)
+{
+  if (!((flags & CCF_CAST) || d == s)) {
+    CTInfo dqual = 0, squal = 0;
+    d = cconv_childqual(cts, d, &dqual);
+    if (!ctype_isstruct(s->info))
+      s = cconv_childqual(cts, s, &squal);
+    if ((flags & CCF_SAME)) {
+      if (dqual != squal)
+        return 0;  /* Different qualifiers. */
+    } else {
+      if ((dqual & squal) != squal)
+        return 0;  /* Discarded qualifiers. */
+      if (ctype_isvoid(d->info) || ctype_isvoid(s->info))
+        return 1;  /* Converting to/from void * is always ok. */
+    }
+    if (ctype_type(d->info) != ctype_type(s->info) ||
+        d->size != s->size)
+      return 0;  /* Different type or different size. */
+    if (ctype_isnum(d->info)) {
+      if (((d->info ^ s->info) & (CTF_BOOL|CTF_FP)))
+        return 0;  /* Different numeric types. */
+    } else if (ctype_ispointer(d->info)) {
+      /* Check child types for compatibility. */
+      return cconv_compatptr(cts, d, s, flags|CCF_SAME);
+    } else if (ctype_isstruct(d->info)) {
+      if (d != s)
+        return 0;  /* Must be exact same type for struct/union. */
+    } else if (ctype_isfunc(d->info)) {
+      /* NYI: structural equality of functions. */
+    }
+  }
+  return 1;  /* Types are compatible. */
+}
+
+/* -- C type to C type conversion ----------------------------------------- */
+
+/* Convert C type to C type. Caveat: expects to get the raw CType!
+**
+** Note: This is only used by the interpreter and not optimized at all.
+** The JIT compiler will do a much better job specializing for each case.
+*/
+void lj_cconv_ct_ct(CTState *cts, CType *d, CType *s,
+                    uint8_t *dp, uint8_t *sp, CTInfo flags)
+{
+  CTSize dsize = d->size, ssize = s->size;
+  CTInfo dinfo = d->info, sinfo = s->info;
+  void *tmpptr;
+
+  lua_assert(!ctype_isenum(dinfo) && !ctype_isenum(sinfo));
+  lua_assert(!ctype_isattrib(dinfo) && !ctype_isattrib(sinfo));
+
+  if (ctype_type(dinfo) > CT_MAYCONVERT || ctype_type(sinfo) > CT_MAYCONVERT)
+    goto err_conv;
+
+  /* Some basic sanity checks. */
+  lua_assert(!ctype_isnum(dinfo) || dsize > 0);
+  lua_assert(!ctype_isnum(sinfo) || ssize > 0);
+  lua_assert(!ctype_isbool(dinfo) || dsize == 1);
+  lua_assert(!ctype_isbool(sinfo) || ssize == 1);
+  lua_assert(!ctype_isinteger(dinfo) || (1u<<lj_fls(dsize)) == dsize);
+  lua_assert(!ctype_isinteger(sinfo) || (1u<<lj_fls(ssize)) == ssize);
+
+  switch (cconv_idx2(dinfo, sinfo)) {
+  /* Destination is a bool. */
+  case CCX(B, B):
+    *dp = *sp;  /* Source operand already normalized. */
+    break;
+  case CCX(B, I):
+  case CCX(B, P): {
+    MSize i;
+    uint8_t b = 0;
+    for (i = 0; i < ssize; i++) b |= sp[i];
+    *dp = (b != 0);
+    break;
+    }
+  case CCX(B, F): {
+    uint8_t b;
+    if (ssize == sizeof(double)) b = (*(double *)sp != 0);
+    else if (ssize == sizeof(float)) b = (*(float *)sp != 0);
+    else goto err_conv;  /* NYI: long double. */
+    *dp = b;
+    break;
+    }
+  case CCX(B, C): {
+    CType *sc = ctype_child(cts, s);
+    uint8_t c;
+    lj_cconv_ct_ct(cts, d, sc, &c, sp, flags);
+    lj_cconv_ct_ct(cts, d, sc, dp, sp + sc->size, flags);
+    *dp = (*dp | c);
+    break;
+    }
+  case CCX(B, A):
+    *dp = (sp != (uint8_t *)0);
+    break;
+
+  /* Destination is an integer. */
+  case CCX(I, B):
+  case CCX(I, I):
+  conv_I_I:
+    if (dsize > ssize) {  /* Zero-extend or sign-extend LSB. */
+#if LJ_LE
+      uint8_t fill = (!(sinfo & CTF_UNSIGNED) && (sp[ssize-1]&0x80)) ? 0xff : 0;
+      memcpy(dp, sp, ssize);
+      memset(dp + ssize, fill, dsize-ssize);
+#else
+      uint8_t fill = (!(sinfo & CTF_UNSIGNED) && (sp[0]&0x80)) ? 0xff : 0;
+      memset(dp, fill, dsize-ssize);
+      memcpy(dp + (dsize-ssize), sp, ssize);
+#endif
+    } else {  /* Copy LSB. */
+#if LJ_LE
+      memcpy(dp, sp, dsize);
+#else
+      memcpy(dp, sp + (ssize-dsize), dsize);
+#endif
+    }
+    break;
+  case CCX(I, F): {
+    double n;  /* Always convert via double. */
+  conv_I_F:
+    /* Convert source to double. */
+    if (ssize == sizeof(double)) n = *(double *)sp;
+    else if (ssize == sizeof(float)) n = (double)*(float *)sp;
+    else goto err_conv;  /* NYI: long double. */
+    /* Then convert double to integer. */
+    /* The conversion must exactly match the semantics of JIT-compiled code! */
+    if (dsize < 4 || (dsize == 4 && !(dinfo & CTF_UNSIGNED))) {
+      int32_t i = (int32_t)n;
+      if (dsize == 4) *(int32_t *)dp = i;
+      else if (dsize == 2) *(int16_t *)dp = (int16_t)i;
+      else *(int8_t *)dp = (int8_t)i;
+    } else if (dsize == 4) {
+      *(uint32_t *)dp = (uint32_t)n;
+    } else if (dsize == 8) {
+      if (!(dinfo & CTF_UNSIGNED))
+        *(int64_t *)dp = (int64_t)n;
+#ifdef _MSC_VER
+      else if (n >= 9223372036854775808.0)  /* They think it's a feature. */
+        *(uint64_t *)dp = (uint64_t)(int64_t)(n - 9223372036854775808.0) +
+                          U64x(80000000,00000000);
+#endif
+      else
+        *(uint64_t *)dp = (uint64_t)n;
+    } else {
+      goto err_conv;  /* NYI: conversion to >64 bit integers. */
+    }
+    break;
+    }
+  case CCX(I, C):
+    s = ctype_child(cts, s);
+    sinfo = s->info;
+    ssize = s->size;
+    goto conv_I_F;  /* Just convert re. */
+  case CCX(I, P):
+    if (!(flags & CCF_CAST)) goto err_conv;
+    sinfo = CTINFO(CT_NUM, CTF_UNSIGNED);
+    goto conv_I_I;
+  case CCX(I, A):
+    if (!(flags & CCF_CAST)) goto err_conv;
+    sinfo = CTINFO(CT_NUM, CTF_UNSIGNED);
+    ssize = CTSIZE_PTR;
+    tmpptr = sp;
+    sp = (uint8_t *)&tmpptr;
+    goto conv_I_I;
+
+  /* Destination is a floating-point number. */
+  case CCX(F, B):
+  case CCX(F, I): {
+    double n;  /* Always convert via double. */
+  conv_F_I:
+    /* First convert source to double. */
+    /* The conversion must exactly match the semantics of JIT-compiled code! */
+    if (ssize < 4 || (ssize == 4 && !(sinfo & CTF_UNSIGNED))) {
+      int32_t i;
+      if (ssize == 4) {
+        i = *(int32_t *)sp;
+      } else if (!(sinfo & CTF_UNSIGNED)) {
+        if (ssize == 2) i = *(int16_t *)sp;
+        else i = *(int8_t *)sp;
+      } else {
+        if (ssize == 2) i = *(uint16_t *)sp;
+        else i = *(uint8_t *)sp;
+      }
+      n = (double)i;
+    } else if (ssize == 4) {
+      n = (double)*(uint32_t *)sp;
+    } else if (ssize == 8) {
+      if (!(sinfo & CTF_UNSIGNED)) n = (double)*(int64_t *)sp;
+      else n = (double)*(uint64_t *)sp;
+    } else {
+      goto err_conv;  /* NYI: conversion from >64 bit integers. */
+    }
+    /* Convert double to destination. */
+    if (dsize == sizeof(double)) *(double *)dp = n;
+    else if (dsize == sizeof(float)) *(float *)dp = (float)n;
+    else goto err_conv;  /* NYI: long double. */
+    break;
+    }
+  case CCX(F, F): {
+    double n;  /* Always convert via double. */
+  conv_F_F:
+    if (ssize == dsize) goto copyval;
+    /* Convert source to double. */
+    if (ssize == sizeof(double)) n = *(double *)sp;
+    else if (ssize == sizeof(float)) n = (double)*(float *)sp;
+    else goto err_conv;  /* NYI: long double. */
+    /* Convert double to destination. */
+    if (dsize == sizeof(double)) *(double *)dp = n;
+    else if (dsize == sizeof(float)) *(float *)dp = (float)n;
+    else goto err_conv;  /* NYI: long double. */
+    break;
+    }
+  case CCX(F, C):
+    s = ctype_child(cts, s);
+    sinfo = s->info;
+    ssize = s->size;
+    goto conv_F_F;  /* Ignore im, and convert from re. */
+
+  /* Destination is a complex number. */
+  case CCX(C, I):
+    d = ctype_child(cts, d);
+    dinfo = d->info;
+    dsize = d->size;
+    memset(dp + dsize, 0, dsize);  /* Clear im. */
+    goto conv_F_I;  /* Convert to re. */
+  case CCX(C, F):
+    d = ctype_child(cts, d);
+    dinfo = d->info;
+    dsize = d->size;
+    memset(dp + dsize, 0, dsize);  /* Clear im. */
+    goto conv_F_F;  /* Convert to re. */
+
+  case CCX(C, C):
+    if (dsize != ssize) {  /* Different types: convert re/im separately. */
+      CType *dc = ctype_child(cts, d);
+      CType *sc = ctype_child(cts, s);
+      lj_cconv_ct_ct(cts, dc, sc, dp, sp, flags);
+      lj_cconv_ct_ct(cts, dc, sc, dp + dc->size, sp + sc->size, flags);
+      return;
+    }
+    goto copyval;  /* Otherwise this is easy. */
+
+  /* Destination is a vector. */
+  case CCX(V, I):
+  case CCX(V, F):
+  case CCX(V, C): {
+    CType *dc = ctype_child(cts, d);
+    CTSize esize;
+    /* First convert the scalar to the first element. */
+    lj_cconv_ct_ct(cts, dc, s, dp, sp, flags);
+    /* Then replicate it to the other elements (splat). */
+    for (sp = dp, esize = dc->size; dsize > esize; dsize -= esize) {
+      dp += esize;
+      memcpy(dp, sp, esize);
+    }
+    break;
+    }
+
+  case CCX(V, V):
+    /* Copy same-sized vectors, even for different lengths/element-types. */
+    if (dsize != ssize) goto err_conv;
+    goto copyval;
+
+  /* Destination is a pointer. */
+  case CCX(P, I):
+    if (!(flags & CCF_CAST)) goto err_conv;
+    dinfo = CTINFO(CT_NUM, CTF_UNSIGNED);
+    goto conv_I_I;
+
+  case CCX(P, F):
+    if (!(flags & CCF_CAST) || !(flags & CCF_FROMTV)) goto err_conv;
+    dinfo = CTINFO(CT_NUM, CTF_UNSIGNED);
+    goto conv_I_F;
+
+  case CCX(P, P):
+    if (!cconv_compatptr(cts, d, s, flags)) goto err_conv;
+    cdata_setptr(dp, dsize, cdata_getptr(sp, ssize));
+    break;
+
+  case CCX(P, A):
+  case CCX(P, S):
+    if (!cconv_compatptr(cts, d, s, flags)) goto err_conv;
+    cdata_setptr(dp, dsize, sp);
+    break;
+
+  /* Destination is an array. */
+  case CCX(A, A):
+    if ((flags & CCF_CAST) || (d->info & CTF_VLA) || d->size != s->size ||
+        d->size == CTSIZE_INVALID || !cconv_compatptr(cts, d, s, flags))
+      goto err_conv;
+    goto copyval;
+
+  /* Destination is a struct/union. */
+  case CCX(S, S):
+    if ((flags & CCF_CAST) || (d->info & CTF_VLA) || d != s)
+      goto err_conv;  /* Must be exact same type. */
+copyval:  /* Copy value. */
+    lua_assert(dsize == ssize);
+    memcpy(dp, sp, dsize);
+    break;
+
+  default:
+  err_conv:
+    cconv_err_conv(cts, d, s, flags);
+  }
+}
+
+/* -- C type to TValue conversion ----------------------------------------- */
+
+/* Copy value to new cdata. Strip attributes and qualifiers. */
+static GCcdata *cconv_copyval(CTState *cts, CTypeID id, void *sp)
+{
+  CType *ct = ctype_raw(cts, id);
+  CTInfo info = ct->info;
+  CTSize size = ct->size;
+  GCcdata *cd;
+  lua_assert(ctype_isnum(info) || ctype_isenum(info) ||
+             ctype_isptr(info) || ctype_isvalarray(info));
+  if (LJ_UNLIKELY((info & CTF_QUAL))) {  /* Any qualifiers to strip? */
+    if (ctype_isarray(info)) {
+      CType *cct = ctype_child(cts, ct);
+      id = lj_ctype_intern(cts, (cct->info & ~CTF_QUAL), cct->size);
+      info = ((info & ~CTMASK_CID) + id);
+    }
+    id = lj_ctype_intern(cts, (info & ~CTF_QUAL), size);
+  }
+  cd = lj_cdata_new(cts, id, size);
+  memcpy(cdataptr(cd), sp, size);
+  return cd;
+}
+
+/* Convert C type to TValue. Caveat: expects to get the raw CType! */
+void lj_cconv_tv_ct(CTState *cts, CType *s, CTypeID sid,
+                    TValue *o, uint8_t *sp)
+{
+  CTInfo sinfo = s->info;
+  lua_assert(!ctype_isenum(sinfo));
+  if (ctype_isnum(sinfo)) {
+    uint8_t tmpbool;
+    uint8_t *dp;
+    CTypeID did;
+    if (!ctype_isbool(sinfo)) {
+      if (ctype_isinteger(sinfo) && s->size > 4) goto copyval;
+      dp = (uint8_t *)&o->n;
+      did = CTID_DOUBLE;
+    } else {
+      dp = &tmpbool;
+      did = CTID_BOOL;
+    }
+    lj_cconv_ct_ct(cts, ctype_get(cts, did), s, dp, sp, 0);
+    /* Numbers are NOT canonicalized here! Beware of uninitialized data. */
+    if (did == CTID_BOOL)
+      setboolV(o, tmpbool);
+    else
+      lua_assert(tvisnum(o));
+  } else if (ctype_isrefarray(sinfo) || ctype_isstruct(sinfo)) {
+    /* Create reference. */
+    setcdataV(cts->L, o, lj_cdata_newref(cts, sp, sid));
+  } else {
+  copyval:  /* Copy value. */
+    setcdataV(cts->L, o, cconv_copyval(cts, sid, sp));
+  }
+}
+
+/* Convert bitfield to TValue. */
+void lj_cconv_tv_bf(CTState *cts, CType *s, TValue *o, uint8_t *sp)
+{
+  CTInfo info = s->info;
+  CTSize pos, bsz;
+  uint32_t val;
+  lua_assert(ctype_isbitfield(info));
+  /* NYI: packed bitfields may cause misaligned reads. */
+  switch (ctype_bitcsz(info)) {
+  case 4: val = *(uint32_t *)sp; break;
+  case 2: val = *(uint16_t *)sp; break;
+  case 1: val = *(uint8_t *)sp; break;
+  default: lua_assert(0); val = 0; break;
+  }
+  /* Check if a packed bitfield crosses a container boundary. */
+  pos = ctype_bitpos(info);
+  bsz = ctype_bitbsz(info);
+  lua_assert(pos < 8*ctype_bitcsz(info));
+  lua_assert(bsz > 0 && bsz <= 8*ctype_bitcsz(info));
+  if (pos + bsz > 8*ctype_bitcsz(info))
+    lj_err_caller(cts->L, LJ_ERR_FFI_NYIPACKBIT);
+  if (!(info & CTF_BOOL)) {
+    CTSize shift = 32 - bsz;
+    if (!(info & CTF_UNSIGNED))
+      setnumV(o, (lua_Number)((int32_t)(val << (shift-pos)) >> shift));
+    else
+      setnumV(o, (lua_Number)((val << (shift-pos)) >> shift));
+  } else {
+    lua_assert(bsz == 1);
+    setboolV(o, (val >> pos) & 1);
+  }
+}
+
+/* -- TValue to C type conversion ----------------------------------------- */
+
+/* Convert table to array. */
+static void cconv_array_tab(CTState *cts, CType *d,
+                            uint8_t *dp, GCtab *t, CTInfo flags)
+{
+  int32_t i;
+  CType *dc = ctype_rawchild(cts, d);  /* Array element type. */
+  CTSize size = d->size, esize = dc->size, ofs = 0;
+  for (i = 0; ; i++) {
+    TValue *tv = (TValue *)lj_tab_getint(t, i);
+    if (!tv || tvisnil(tv)) {
+      if (i == 0) continue;  /* Try again for 1-based tables. */
+      break;  /* Stop at first nil. */
+    }
+    if (ofs >= size)
+      cconv_err_initov(cts, d);
+    lj_cconv_ct_tv(cts, dc, dp + ofs, tv, flags);
+    ofs += esize;
+  }
+  if (size != CTSIZE_INVALID) {  /* Only fill up arrays with known size. */
+    if (ofs == esize) {  /* Replicate a single element. */
+      for (; ofs < size; ofs += esize) memcpy(dp + ofs, dp, esize);
+    } else {  /* Otherwise fill the remainder with zero. */
+      memset(dp + ofs, 0, size - ofs);
+    }
+  }
+}
+
+/* Convert table to sub-struct/union. */
+static void cconv_substruct_tab(CTState *cts, CType *d, uint8_t *dp,
+                                GCtab *t, int32_t *ip, CTInfo flags)
+{
+  CTypeID id = d->sib;
+  while (id) {
+    CType *df = ctype_get(cts, id);
+    id = df->sib;
+    if (ctype_isfield(df->info) || ctype_isbitfield(df->info)) {
+      TValue *tv;
+      int32_t i = *ip;
+      if (!gcref(df->name)) continue;  /* Ignore unnamed fields. */
+      if (i >= 0) {
+      retry:
+        tv = (TValue *)lj_tab_getint(t, i);
+        if (!tv || tvisnil(tv)) {
+          if (i == 0) { i = 1; goto retry; }  /* 1-based tables. */
+          break;  /* Stop at first nil. */
+        }
+        *ip = i + 1;
+      } else {
+        tv = (TValue *)lj_tab_getstr(t, gco2str(gcref(df->name)));
+        if (!tv || tvisnil(tv)) continue;
+      }
+      if (ctype_isfield(df->info))
+        lj_cconv_ct_tv(cts, ctype_rawchild(cts, df), dp+df->size, tv, flags);
+      else
+        lj_cconv_bf_tv(cts, df, dp+df->size, tv);
+      if ((d->info & CTF_UNION)) break;
+    } else if (ctype_isxattrib(df->info, CTA_SUBTYPE)) {
+      cconv_substruct_tab(cts, ctype_child(cts, df), dp+df->size, t, ip, flags);
+    }  /* Ignore all other entries in the chain. */
+  }
+}
+
+/* Convert table to struct/union. */
+static void cconv_struct_tab(CTState *cts, CType *d,
+                             uint8_t *dp, GCtab *t, CTInfo flags)
+{
+  int32_t i = 0;
+  memset(dp, 0, d->size);  /* Much simpler to clear the struct first. */
+  if (t->hmask) i = -1; else if (t->asize == 0) return;  /* Fast exit. */
+  cconv_substruct_tab(cts, d, dp, t, &i, flags);
+}
+
+/* Convert TValue to C type. Caveat: expects to get the raw CType! */
+void lj_cconv_ct_tv(CTState *cts, CType *d,
+                    uint8_t *dp, TValue *o, CTInfo flags)
+{
+  CTypeID sid = CTID_P_VOID;
+  CType *s;
+  void *tmpptr;
+  uint8_t tmpbool, *sp = (uint8_t *)&tmpptr;
+  if (LJ_LIKELY(tvisnum(o))) {
+    sp = (uint8_t *)&o->n;
+    sid = CTID_DOUBLE;
+    flags |= CCF_FROMTV;
+  } else if (tviscdata(o)) {
+    sp = cdataptr(cdataV(o));
+    sid = cdataV(o)->typeid;
+    s = ctype_get(cts, sid);
+    if (ctype_isref(s->info)) {  /* Resolve reference for value. */
+      lua_assert(s->size == CTSIZE_PTR);
+      sp = *(void **)sp;
+      sid = ctype_cid(s->info);
+    }
+    s = ctype_raw(cts, sid);
+    if (ctype_isenum(s->info)) s = ctype_child(cts, s);
+    goto doconv;
+  } else if (tvisstr(o)) {
+    GCstr *str = strV(o);
+    if (ctype_isenum(d->info)) {  /* Match string against enum constant. */
+      CTSize ofs;
+      CType *cct = lj_ctype_getfield(cts, d, str, &ofs);
+      if (!cct || !ctype_isconstval(cct->info))
+        goto err_conv;
+      lua_assert(d->size == 4);
+      sp = (uint8_t *)&cct->size;
+      sid = ctype_cid(cct->info);
+    } else if (ctype_isrefarray(d->info)) {  /* Copy string to array. */
+      CType *dc = ctype_rawchild(cts, d);
+      CTSize sz = str->len+1;
+      if (!ctype_isinteger(dc->info) || dc->size != 1)
+        goto err_conv;
+      if (d->size != 0 && d->size < sz) {
+        sz = d->size-1;
+        dp[sz] = '\0';
+      }
+      memcpy(dp, strdata(str), sz);
+      return;
+    } else {  /* Otherwise pass it as a const char[]. */
+      sp = (uint8_t *)strdata(str);
+      sid = CTID_A_CCHAR;
+      flags |= CCF_FROMTV;
+    }
+  } else if (tvistab(o)) {
+    if (ctype_isarray(d->info)) {
+      cconv_array_tab(cts, d, dp, tabV(o), flags);
+      return;
+    } else if (ctype_isstruct(d->info)) {
+      cconv_struct_tab(cts, d, dp, tabV(o), flags);
+      return;
+    } else {
+      goto err_conv;
+    }
+  } else if (tvisbool(o)) {
+    tmpbool = boolV(o);
+    sp = &tmpbool;
+    sid = CTID_BOOL;
+  } else if (tvisnil(o)) {
+    tmpptr = (void *)0;
+  } else if (tvisudata(o)) {
+    tmpptr = uddata(udataV(o));
+  } else if (tvislightud(o)) {
+    tmpptr = lightudV(o);
+  } else {
+  err_conv:
+    cconv_err_convtv(cts, d, o);
+  }
+  s = ctype_get(cts, sid);
+doconv:
+  if (ctype_isenum(d->info)) d = ctype_child(cts, d);
+  lj_cconv_ct_ct(cts, d, s, dp, sp, flags);
+}
+
+/* Convert TValue to bitfield. */
+void lj_cconv_bf_tv(CTState *cts, CType *d, uint8_t *dp, TValue *o)
+{
+  CTInfo info = d->info;
+  CTSize pos, bsz;
+  uint32_t val, mask;
+  lua_assert(ctype_isbitfield(info));
+  if ((info & CTF_BOOL)) {
+    uint8_t tmpbool;
+    lua_assert(ctype_bitbsz(info) == 1);
+    lj_cconv_ct_tv(cts, ctype_get(cts, CTID_BOOL), &tmpbool, o, 0);
+    val = tmpbool;
+  } else {
+    CTypeID did = (info & CTF_UNSIGNED) ? CTID_UINT32 : CTID_INT32;
+    lj_cconv_ct_tv(cts, ctype_get(cts, did), (uint8_t *)&val, o, 0);
+  }
+  pos = ctype_bitpos(info);
+  bsz = ctype_bitbsz(info);
+  lua_assert(pos < 8*ctype_bitcsz(info));
+  lua_assert(bsz > 0 && bsz <= 8*ctype_bitcsz(info));
+  /* Check if a packed bitfield crosses a container boundary. */
+  if (pos + bsz > 8*ctype_bitcsz(info))
+    lj_err_caller(cts->L, LJ_ERR_FFI_NYIPACKBIT);
+  mask = ((1u << bsz) - 1u) << pos;
+  val = (val << pos) & mask;
+  /* NYI: packed bitfields may cause misaligned reads/writes. */
+  switch (ctype_bitcsz(info)) {
+  case 4: *(uint32_t *)dp = (*(uint32_t *)dp & ~mask) | (uint32_t)val; break;
+  case 2: *(uint16_t *)dp = (*(uint16_t *)dp & ~mask) | (uint16_t)val; break;
+  case 1: *(uint8_t *)dp = (*(uint8_t *)dp & ~mask) | (uint8_t)val; break;
+  default: lua_assert(0); break;
+  }
+}
+
+/* -- Initialize C type with TValues -------------------------------------- */
+
+/* Initialize an array with TValues. */
+static void cconv_array_init(CTState *cts, CType *d, CTSize sz, uint8_t *dp,
+                             TValue *o, MSize len)
+{
+  CType *dc = ctype_rawchild(cts, d);  /* Array element type. */
+  CTSize ofs, esize = dc->size;
+  MSize i;
+  if (len*esize > sz)
+    cconv_err_initov(cts, d);
+  for (i = 0, ofs = 0; i < len; i++, ofs += esize)
+    lj_cconv_ct_tv(cts, dc, dp + ofs, o + i, 0);
+  if (ofs == esize) {  /* Replicate a single element. */
+    for (; ofs < sz; ofs += esize) memcpy(dp + ofs, dp, esize);
+  } else {  /* Otherwise fill the remainder with zero. */
+    memset(dp + ofs, 0, sz - ofs);
+  }
+}
+
+/* Initialize a sub-struct/union with TValues. */
+static void cconv_substruct_init(CTState *cts, CType *d, uint8_t *dp,
+                                 TValue *o, MSize len, MSize *ip)
+{
+  CTypeID id = d->sib;
+  while (id) {
+    CType *df = ctype_get(cts, id);
+    id = df->sib;
+    if (ctype_isfield(df->info) || ctype_isbitfield(df->info)) {
+      MSize i = *ip;
+      if (!gcref(df->name)) continue;  /* Ignore unnamed fields. */
+      if (i >= len) break;
+      *ip = i + 1;
+      if (ctype_isfield(df->info))
+        lj_cconv_ct_tv(cts, ctype_rawchild(cts, df), dp+df->size, o + i, 0);
+      else
+        lj_cconv_bf_tv(cts, df, dp+df->size, o + i);
+      if ((d->info & CTF_UNION)) break;
+    } else if (ctype_isxattrib(df->info, CTA_SUBTYPE)) {
+      cconv_substruct_init(cts, ctype_child(cts, df), dp+df->size, o, len, ip);
+    }  /* Ignore all other entries in the chain. */
+  }
+}
+
+/* Initialize a struct/union with TValues. */
+static void cconv_struct_init(CTState *cts, CType *d, CTSize sz, uint8_t *dp,
+                              TValue *o, MSize len)
+{
+  MSize i = 0;
+  memset(dp, 0, sz);  /* Much simpler to clear the struct first. */
+  cconv_substruct_init(cts, d, dp, o, len, &i);
+  if (i < len)
+    cconv_err_initov(cts, d);
+}
+
+/* Check whether to use a multi-value initializer.
+** This is true if an aggregate is to be initialized with a value.
+** Valarrays are treated as values here so ct_tv handles (V|C, I|F).
+*/
+static int cconv_multi_init(CTState *cts, CType *d, TValue *o)
+{
+  if (!(ctype_isrefarray(d->info) || ctype_isstruct(d->info)))
+    return 0;  /* Destination is not an aggregate. */
+  if (tvistab(o) || (tvisstr(o) && !ctype_isstruct(d->info)))
+    return 0;  /* Initializer is not a value. */
+  if (tviscdata(o)) {
+    CTInfo info = lj_ctype_rawref(cts, cdataV(o)->typeid)->info;
+    if (ctype_isrefarray(info) || ctype_isstruct(info))
+      return 0;  /* Initializer is not a value. */
+  }
+  return 1;  /* Otherwise the initializer is a value. */
+}
+
+/* Initialize C type with TValues. Caveat: expects to get the raw CType! */
+void lj_cconv_ct_init(CTState *cts, CType *d, CTSize sz,
+                      uint8_t *dp, TValue *o, MSize len)
+{
+  if (len == 0)
+    memset(dp, 0, sz);
+  else if (len == 1 && !cconv_multi_init(cts, d, o))
+    lj_cconv_ct_tv(cts, d, dp, o, 0);
+  else if (ctype_isarray(d->info))  /* Also handles valarray init with len>1. */
+    cconv_array_init(cts, d, sz, dp, o, len);
+  else if (ctype_isstruct(d->info))
+    cconv_struct_init(cts, d, sz, dp, o, len);
+  else
+    cconv_err_initov(cts, d);
+}
+
+#endif