From d78034230ab787043350acd5fd6bd9f08cceab56 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 4 May 2017 21:19:13 -0700
Subject: ffi: map (array n bchar) to Lisp string.

* ffi.c (struct txr_ffi_type): New bitfield flag, bchar_conv.
(ffi_array_in, ffi_array_get): Handle bchar_conv.
(ffi_type_compile): Set bchar_conv flag for array of bchar.

* lib.c (string_8bit_size): New function.

* lib.h (string_8bit_size): Declared.
---
 ffi.c | 26 ++++++++++++++++++++++++++
 lib.c |  9 +++++++++
 lib.h |  1 +
 3 files changed, 36 insertions(+)

diff --git a/ffi.c b/ffi.c
index 0cccd46e..a6c872e9 100644
--- a/ffi.c
+++ b/ffi.c
@@ -96,6 +96,7 @@ struct txr_ffi_type {
   unsigned null_term : 1;
   unsigned char_conv : 1;
   unsigned wchar_conv : 1;
+  unsigned bchar_conv : 1;
   void (*put)(struct txr_ffi_type *, val obj, mem_t *dst, val self);
   val (*get)(struct txr_ffi_type *, mem_t *src, val self);
   val (*in)(struct txr_ffi_type *, mem_t *src, val obj, val self);
@@ -959,6 +960,19 @@ static val ffi_array_in(struct txr_ffi_type *tft, mem_t *src, val vec,
       }
     }
     vec = if3(vec, replace(vec, str, zero, t), str);
+  } else if (tft->bchar_conv) {
+    val str;
+
+    if (nelem == 0) {
+      str = null_string;
+    } else {
+      const unsigned char *chptr = coerce(const unsigned char *, src);
+      if (chptr[tft->size - 1] == 0)
+        str = string_8bit(chptr);
+      else
+        str = string_8bit_size(chptr, tft->size);
+    }
+    vec = if3(vec, replace(vec, str, zero, t), str);
   } else {
     ucnum offs = 0;
     struct txr_ffi_type *etft = ffi_type_struct(eltype);
@@ -1060,6 +1074,16 @@ static val ffi_array_get(struct txr_ffi_type *tft, mem_t *src, val self)
         return init_str(ustr, wchptr);
       }
     }
+  } else if (tft->bchar_conv) {
+    if (nelem == 0) {
+      return null_string;
+    } else {
+      const unsigned char *chptr = coerce(const unsigned char *, src);
+      if (chptr[tft->size - 1] == 0)
+        return string_8bit(chptr);
+      else
+        return string_8bit_size(chptr, tft->size);
+    }
   } else {
     cnum znelem = if3(tft->null_term && nelem > 0, nelem - 1, nelem);
     val vec = vector(num_fast(znelem), nil);
@@ -1295,6 +1319,8 @@ val ffi_type_compile(val syntax)
           tft->char_conv = 1;
         else if (eltype_syntax == wchar_s)
           tft->wchar_conv = 1;
+        else if (eltype_syntax == bchar_s)
+          tft->bchar_conv = 1;
         return type;
       }
     } else if (sym == ptr_in_s) {
diff --git a/lib.c b/lib.c
index 86485e3c..95a93c01 100644
--- a/lib.c
+++ b/lib.c
@@ -3300,6 +3300,15 @@ val string_8bit(const unsigned char *str)
   return string_own(wstr);
 }
 
+val string_8bit_size(const unsigned char *str, size_t sz)
+{
+  size_t i;
+  wchar_t *wstr = chk_wmalloc(sz);
+  for (i = 0; i < sz; i++)
+    wstr[i] = str[i];
+  return string_own(wstr);
+}
+
 val mkstring(val len, val ch)
 {
   size_t l = c_num(len);
diff --git a/lib.h b/lib.h
index 4875ef2a..814b0621 100644
--- a/lib.h
+++ b/lib.h
@@ -726,6 +726,7 @@ val string_own(wchar_t *str);
 val string(const wchar_t *str);
 val string_utf8(const char *str);
 val string_8bit(const unsigned char *str);
+val string_8bit_size(const unsigned char *str, size_t sz);
 val mkstring(val len, val ch);
 val mkustring(val len); /* must initialize immediately with init_str! */
 val init_str(val str, const wchar_t *);
-- 
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