From f226f44490a31e88017b2c3e2032d6926ef1c336 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 11 May 2017 06:26:18 -0700
Subject: ffi: encode-side character array specializations.

If the object being encoded is a string, and the array element
type is char, wchar or bchar, then encode a string, honoring
null termination flag. Unused space in the destination array
is filled with zeros.

* ffi.c (ffi_char_array_put, ffi_wchar_array_put,
ffi_bchar_array_put): New functions.
(ffi_array_put, ffi_array_out): Use new functions under
the right conditions.
---
 ffi.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

diff --git a/ffi.c b/ffi.c
index fcf74f9e..dae84c3d 100644
--- a/ffi.c
+++ b/ffi.c
@@ -1012,6 +1012,24 @@ static val ffi_char_array_get(struct txr_ffi_type *tft, mem_t *src,
   }
 }
 
+static void ffi_char_array_put(struct txr_ffi_type *tft, val str, mem_t *dst,
+                               cnum nelem)
+{
+  int nt = tft->null_term;
+  const wchar_t *wstr = c_str(str);
+  size_t needed = utf8_to_buf(0, wstr, nt);
+
+  if (needed <= nelem) {
+    utf8_to_buf(dst, wstr, nt);
+    memset(dst + needed, 0, nelem - needed);
+  } else {
+    char *u8str = utf8_dup_to(wstr);
+    memcpy(dst, u8str, nelem);
+    dst[nelem - 1] = 0;
+    free(u8str);
+  }
+}
+
 static val ffi_wchar_array_get(struct txr_ffi_type *tft, mem_t *src,
                                cnum nelem)
 {
@@ -1029,6 +1047,15 @@ static val ffi_wchar_array_get(struct txr_ffi_type *tft, mem_t *src,
   }
 }
 
+static void ffi_wchar_array_put(struct txr_ffi_type *tft, val str, mem_t *dst,
+                                cnum nelem)
+{
+  const wchar_t *wstr = c_str(str);
+  wcsncpy(coerce(wchar_t *, dst), wstr, nelem);
+  if (tft->null_term)
+    dst[nelem - 1] = 0;
+}
+
 static val ffi_bchar_array_get(struct txr_ffi_type *tft, mem_t *src,
                                cnum nelem)
 {
@@ -1043,6 +1070,28 @@ static val ffi_bchar_array_get(struct txr_ffi_type *tft, mem_t *src,
   }
 }
 
+static void ffi_bchar_array_put(struct txr_ffi_type *tft, val str, mem_t *dst,
+                                cnum nelem, val self)
+{
+  const wchar_t *wstr = c_str(str);
+  cnum i;
+
+  for (i = 0; i < nelem && wstr[i]; i++) {
+    wchar_t wch = wstr[i];
+    if (wch < 0 || wch > 255)
+      uw_throwf(error_s, lit("~a: character ~s out of unsigned 8 bit range"),
+                self, chr(wch), nao);
+    dst[i] = wch;
+  }
+
+  if (i < nelem) {
+    for (; i < nelem; i++)
+      dst[i] = 0;
+  } else if (tft->null_term) {
+    dst[nelem - 1] = 0;
+  }
+}
+
 static val ffi_array_in_common(struct txr_ffi_type *tft, int copy,
                                mem_t *src, val vec, val self, cnum nelem)
 {
@@ -1112,7 +1161,14 @@ static void ffi_array_put_common(struct txr_ffi_type *tft, val vec, mem_t *dst,
 static void ffi_array_put(struct txr_ffi_type *tft, val vec, mem_t *dst,
                           val self)
 {
-  ffi_array_put_common(tft, vec, dst, self, tft->nelem);
+  if (tft->char_conv && stringp(vec))
+    ffi_char_array_put(tft, vec, dst, tft->nelem);
+  else if (tft->wchar_conv && stringp(vec))
+    ffi_wchar_array_put(tft, vec, dst, tft->nelem);
+  else if (tft->bchar_conv && stringp(vec))
+    ffi_bchar_array_put(tft, vec, dst, tft->nelem, self);
+  else
+    ffi_array_put_common(tft, vec, dst, self, tft->nelem);
 }
 
 static void ffi_array_out_common(struct txr_ffi_type *tft, int copy, val vec,
@@ -1144,7 +1200,14 @@ static void ffi_array_out_common(struct txr_ffi_type *tft, int copy, val vec,
 static void ffi_array_out(struct txr_ffi_type *tft, int copy, val vec,
                           mem_t *dst, val self)
 {
-  ffi_array_out_common(tft, copy, vec, dst, self, tft->nelem);
+  if (tft->char_conv && stringp(vec))
+    ffi_char_array_put(tft, vec, dst, tft->nelem);
+  else if (tft->wchar_conv && stringp(vec))
+    ffi_wchar_array_put(tft, vec, dst, tft->nelem);
+  else if (tft->bchar_conv && stringp(vec))
+    ffi_bchar_array_put(tft, vec, dst, tft->nelem, self);
+  else
+    ffi_array_out_common(tft, copy, vec, dst, self, tft->nelem);
 }
 
 static val ffi_array_get_common(struct txr_ffi_type *tft, mem_t *src, val self,
-- 
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