From 79ab1a4baaa98acac43f20fa27db5f04d86cc7cc Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Thu, 23 Dec 2010 17:54:54 +0100
Subject: FFI: Add pointer arithmetic.
---
src/lib_ffi.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
src/lj_cconv.c | 12 +++----
src/lj_cconv.h | 2 ++
3 files changed, 118 insertions(+), 6 deletions(-)
(limited to 'src')
diff --git a/src/lib_ffi.c b/src/lib_ffi.c
index e7108c59..ed73a5fe 100644
--- a/src/lib_ffi.c
+++ b/src/lib_ffi.c
@@ -74,6 +74,41 @@ static void *ffi_checkptr(lua_State *L, int narg, CTypeID id)
return p;
}
+typedef struct FFIArith {
+ uint8_t *p[2];
+ CType *ct[2];
+} FFIArith;
+
+/* Check arguments for arithmetic metamethods. */
+static void ffi_checkarith(lua_State *L, FFIArith *fa)
+{
+ CTState *cts = ctype_cts(L);
+ TValue *o = L->base;
+ MSize i;
+ if (o+1 >= L->top)
+ lj_err_argt(L, 1, LUA_TCDATA);
+ for (i = 0; i < 2; i++, o++) {
+ if (tviscdata(o)) {
+ GCcdata *cd = cdataV(o);
+ CTypeID id = (CTypeID)cd->typeid;
+ CType *ct = ctype_get(cts, id);
+ uint8_t *p = (uint8_t *)cdataptr(cd);
+ if (ctype_isref(ct->info)) {
+ lua_assert(ct->size == CTSIZE_PTR);
+ p = *(uint8_t **)p;
+ id = ctype_cid(ct->info);
+ }
+ fa->ct[i] = ctype_raw(cts, id);
+ fa->p[i] = p;
+ } else if (tvisnum(o)) {
+ fa->ct[i] = ctype_get(cts, CTID_DOUBLE);
+ fa->p[i] = (uint8_t *)&o->n;
+ } else {
+ lj_err_optype(L, o, LJ_ERR_OPARITH);
+ }
+ }
+}
+
/* -- C type metamethods -------------------------------------------------- */
#define LJLIB_MODULE_ffi_meta
@@ -118,6 +153,81 @@ LJLIB_CF(ffi_meta___call) LJLIB_REC(cdata_call)
return 0; /* unreachable */
}
+/* Pointer arithmetic. */
+static int ffi_arith_ptr(lua_State *L, FFIArith *fa, int sub)
+{
+ CTState *cts = ctype_cts(L);
+ CType *ctp = fa->ct[0];
+ uint8_t *pp = fa->p[0];
+ ptrdiff_t idx;
+ CTSize sz;
+ CTypeID id;
+ GCcdata *cd;
+ if (ctype_isptr(ctp->info) || ctype_isrefarray(ctp->info)) {
+ if (sub &&
+ (ctype_isptr(fa->ct[1]->info) || ctype_isrefarray(fa->ct[1]->info))) {
+ /* Pointer difference. */
+ intptr_t diff;
+ if (!lj_cconv_compatptr(cts, ctp, fa->ct[1], CCF_IGNQUAL))
+ lj_err_caller(L, LJ_ERR_FFI_INVTYPE);
+ sz = lj_ctype_size(cts, ctype_cid(ctp->info)); /* Element size. */
+ if (sz == 0 || sz == CTSIZE_INVALID)
+ lj_err_caller(L, LJ_ERR_FFI_INVSIZE);
+ if (ctype_isptr(ctp->info))
+ pp = (uint8_t *)cdata_getptr(pp, ctp->size);
+ if (ctype_isptr(fa->ct[1]->info))
+ fa->p[1] = (uint8_t *)cdata_getptr(fa->p[1], fa->ct[1]->size);
+ diff = ((intptr_t)pp - (intptr_t)fa->p[1]) / (int32_t)sz;
+ /* All valid pointer differences on x64 are in (-2^47, +2^47),
+ ** which fits into a double without loss of precision.
+ */
+ setnumV(L->top-1, (lua_Number)diff);
+ return 1;
+ }
+ lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), fa->ct[1],
+ (uint8_t *)&idx, fa->p[1], 0);
+ if (sub) idx = -idx;
+ } else if (!sub &&
+ (ctype_isptr(fa->ct[1]->info) || ctype_isrefarray(fa->ct[1]->info))) {
+ /* Swap pointer and index. */
+ ctp = fa->ct[1]; pp = fa->p[1];
+ lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), fa->ct[0],
+ (uint8_t *)&idx, fa->p[0], 0);
+ } else {
+ return 0;
+ }
+ sz = lj_ctype_size(cts, ctype_cid(ctp->info)); /* Element size. */
+ if (sz == CTSIZE_INVALID)
+ lj_err_caller(L, LJ_ERR_FFI_INVSIZE);
+ if (ctype_isptr(ctp->info))
+ pp = (uint8_t *)cdata_getptr(pp, ctp->size);
+ pp += idx*(int32_t)sz; /* Compute pointer + index. */
+ id = lj_ctype_intern(cts, CTINFO(CT_PTR, CTALIGN_PTR|ctype_cid(ctp->info)),
+ CTSIZE_PTR);
+ cd = lj_cdata_new(cts, id, CTSIZE_PTR);
+ *(uint8_t **)cdataptr(cd) = pp;
+ setcdataV(L, L->top-1, cd);
+ return 1;
+}
+
+LJLIB_CF(ffi_meta___add)
+{
+ FFIArith fa;
+ ffi_checkarith(L, &fa);
+ if (!ffi_arith_ptr(L, &fa, 0))
+ lj_err_caller(L, LJ_ERR_FFI_INVTYPE);
+ return 1;
+}
+
+LJLIB_CF(ffi_meta___sub)
+{
+ FFIArith fa;
+ ffi_checkarith(L, &fa);
+ if (!ffi_arith_ptr(L, &fa, 1))
+ lj_err_caller(L, LJ_ERR_FFI_INVTYPE);
+ return 1;
+}
+
LJLIB_CF(ffi_meta___tostring)
{
GCcdata *cd = ffi_checkcdata(L, 1);
diff --git a/src/lj_cconv.c b/src/lj_cconv.c
index 85fd57e5..e5abf3e9 100644
--- a/src/lj_cconv.c
+++ b/src/lj_cconv.c
@@ -63,7 +63,7 @@ static CType *cconv_childqual(CTState *cts, CType *ct, CTInfo *qual)
/* 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)
+int lj_cconv_compatptr(CTState *cts, CType *d, CType *s, CTInfo flags)
{
if (!((flags & CCF_CAST) || d == s)) {
CTInfo dqual = 0, squal = 0;
@@ -73,7 +73,7 @@ static int cconv_compatptr(CTState *cts, CType *d, CType *s, CTInfo flags)
if ((flags & CCF_SAME)) {
if (dqual != squal)
return 0; /* Different qualifiers. */
- } else {
+ } else if (!(flags & CCF_IGNQUAL)) {
if ((dqual & squal) != squal)
return 0; /* Discarded qualifiers. */
if (ctype_isvoid(d->info) || ctype_isvoid(s->info))
@@ -87,7 +87,7 @@ static int cconv_compatptr(CTState *cts, CType *d, CType *s, CTInfo flags)
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);
+ return lj_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. */
@@ -339,20 +339,20 @@ void lj_cconv_ct_ct(CTState *cts, CType *d, CType *s,
goto conv_I_F;
case CCX(P, P):
- if (!cconv_compatptr(cts, d, s, flags)) goto err_conv;
+ if (!lj_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;
+ if (!lj_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))
+ d->size == CTSIZE_INVALID || !lj_cconv_compatptr(cts, d, s, flags))
goto err_conv;
goto copyval;
diff --git a/src/lj_cconv.h b/src/lj_cconv.h
index 140ce8d6..dd2f2c40 100644
--- a/src/lj_cconv.h
+++ b/src/lj_cconv.h
@@ -46,8 +46,10 @@ static LJ_AINLINE uint32_t cconv_idx(CTInfo info)
#define CCF_CAST 0x00000001u
#define CCF_FROMTV 0x00000002u
#define CCF_SAME 0x00000004u
+#define CCF_IGNQUAL 0x00000008u
+LJ_FUNC int lj_cconv_compatptr(CTState *cts, CType *d, CType *s, CTInfo flags);
LJ_FUNC void lj_cconv_ct_ct(CTState *cts, CType *d, CType *s,
uint8_t *dp, uint8_t *sp, CTInfo flags);
LJ_FUNC void lj_cconv_tv_ct(CTState *cts, CType *s, CTypeID sid,
--
cgit v1.2.3-55-g6feb