New: CRC-32 functions.

* Makefile (OBJS): Add chksums/crc32.o.

* chksum.c (crc32_stream, crc32): New functions.
(chksum_init): Register crc32-stream and crc32 intrinsic
functions.

* chksums/crc32.c, chksums/crc32.h: New files.

* txr.1: Documented.

1 files changed, 87 insertions, 0 deletions

diff --git a/chksum.c b/chksum.c
index 78af6b8d..588bdf92 100644
--- a/chksum.c
+++ b/chksum.c
@@ -44,6 +44,7 @@
 #include "utf8.h"
 #include "buf.h"
 #include "chksums/sha256.h"
+#include "chksums/crc32.h"
 #include "chksum.h"
 
 val sha256_stream(val stream, val nbytes)
@@ -135,8 +136,94 @@ val sha256(val obj)
   }
 }
 
+val crc32_stream(val stream, val nbytes)
+{
+  u32_t crc = 0;
+  val bfsz = num_fast(BUFSIZ);
+  val buf = make_buf(bfsz, nil, nil);
+
+  if (null_or_missing_p(nbytes)) {
+    for (;;) {
+      val read = fill_buf(buf, zero, stream);
+      cnum rd = c_num(read);
+
+      if (!rd)
+        break;
+
+      crc = crc32_cont(buf->b.data, rd, crc);
+    }
+  } else {
+    while (ge(nbytes, bfsz)) {
+      val read = fill_buf(buf, zero, stream);
+      cnum rd = c_num(read);
+
+      if (zerop(read))
+        break;
+
+      crc = crc32_cont(buf->b.data, rd, crc);
+      nbytes = minus(nbytes, read);
+    }
+
+    buf_set_length(buf, nbytes, nil);
+
+    {
+      val read = fill_buf(buf, zero, stream);
+      cnum rd = c_num(read);
+      if (rd)
+        crc = crc32_cont(buf->b.data, rd, crc);
+    }
+  }
+
+  return unum(crc);
+}
+
+static val crc32_buf(val buf, val self)
+{
+  ucnum len = c_unum(buf->b.len);
+  mem_t *data = buf->b.data;
+  const size_t szmax = convert(size_t, -1) / 4 + 1;
+  u32_t crc = 0;
+
+  while (len >= szmax) {
+    crc = crc32_cont(data, szmax, crc);
+    data += szmax;
+    len -= szmax;
+  }
+
+  if (len > 0)
+    crc = crc32_cont(data, len, crc);
+
+  return unum(crc);
+}
+
+static val crc32_str(val str, val self)
+{
+  val s = make_byte_input_stream(str);
+  return crc32_stream(s, nil);
+}
+
+
+val crc32(val obj)
+{
+  val self = lit("sha256");
+
+  switch (type(obj)) {
+  case STR:
+  case LSTR:
+  case LIT:
+    return crc32_str(obj, self);
+  case BUF:
+    return crc32_buf(obj, self);
+  default:
+    uw_throwf(error_s, lit("~a: cannot hash ~s, only buffer and strings"),
+              self, obj, nao);
+  }
+}
+
 void chksum_init(void)
 {
   reg_fun(intern(lit("sha256-stream"), user_package), func_n2o(sha256_stream, 1));
   reg_fun(intern(lit("sha256"), user_package), func_n1(sha256));
+  reg_fun(intern(lit("crc32-stream"), user_package), func_n2o(crc32_stream, 1));
+  reg_fun(intern(lit("crc32"), user_package), func_n1(crc32));
 }