Add crc32 jet (#653)

Adds crc32 jet. This will be used to validate uncompressed gzip data.
urbit/urbit#6997

pkg/noun/BUILD.bazel

@@ -40,6 +40,7 @@ vere_library(
         "@sigsegv",
         "@softfloat",
         "@urcrypt",
+        "@zlib",
     ] + select({
         "@platforms//os:macos": ["//pkg/noun/platform/darwin"],
         "@platforms//os:linux": ["//pkg/noun/platform/linux"],

pkg/noun/jets/e/crc32.c

@@ -0,0 +1,59 @@
+/// @file
+
+#include <stdio.h>
+#include <allocate.h>
+#include "zlib.h"
+
+#include "jets/w.h"
+
+#include "noun.h"
+
+u3_noun
+u3qe_crc32(u3_noun input_octs)
+{
+  u3_atom head = u3h(input_octs);
+  u3_atom tail = u3t(input_octs);
+  c3_w  tel_w = u3r_met(3, tail);
+  c3_w hed_w;
+  if ( c3n == u3r_safe_word(head, &hed_w) ) {
+    return u3m_bail(c3__fail);
+  }
+  c3_y* input;
+
+  if (c3y == u3a_is_cat(tail)) {
+    input = &tail;
+  }
+  else {
+    u3a_atom* vat_u = u3a_to_ptr(tail);
+    input = (c3_y*)vat_u->buf_w;
+  }
+
+  if ( tel_w > hed_w ) {
+    return u3m_error("subtract-underflow");
+  }
+
+  c3_w led_w = hed_w - tel_w;
+  c3_w crc_w = 0;
+
+  crc_w = crc32(crc_w, input, tel_w);
+
+  while ( led_w > 0 ) {
+    c3_y byt_y = 0;
+    crc_w = crc32(crc_w, &byt_y, 1);
+    led_w--;
+  }
+
+  return u3i_word(crc_w);
+}
+
+u3_noun
+u3we_crc32(u3_noun cor)
+{
+  u3_noun a = u3r_at(u3x_sam, cor);
+
+  if ( (u3du(a) == c3y) && (u3ud(u3h(a)) == c3y) && (u3ud(u3t(a)) == c3y) ) {
+    return u3qe_crc32(a);
+  } else {
+    return u3m_bail(c3__exit);
+  }
+}

pkg/noun/jets/tree.c

@@ -270,6 +270,12 @@ static c3_c* _140_hex_lune_ha[] = {
   0
 };
 
+
+static u3j_harm _137_hex__crc32_a[] = {{".2", u3we_crc32}, {}};
+
+static u3j_core _137_hex__crc_d[] = {{"crc32", 7, _137_hex__crc32_a, 0, no_hashes }, {}};
+
+
 static u3j_harm _140_hex_coed__ed_puck_a[] = {{".2", u3wee_puck}, {}};
 static c3_c* _140_hex_coed__ed_puck_ha[] = {
   "1bc694675842345c50b0e20a2193bb5bcbb42f163fc832431a3d1822a81e4c98",
@@ -2346,6 +2352,8 @@ static u3j_core _138_hex_d[] =
   { "leer",  63, _140_hex_leer_a, 0, no_hashes },
   { "loss",  63, _140_hex_loss_a, 0, no_hashes },
   { "lune", 127, _140_hex_lune_a, 0, no_hashes },
+// XX move me to 137 when it exists
+  { "crc", 31, 0, _137_hex__crc_d, no_hashes },
 
   { "coed", 63, 0, _140_hex_coed_d, no_hashes },
   { "aes",  31, 0, _140_hex_aes_d,  no_hashes },

pkg/noun/jets/w.h

@@ -291,6 +291,8 @@
     u3_noun u3wes_gte(u3_noun);
     u3_noun u3wes_gth(u3_noun);
 
+    u3_noun u3we_crc32(u3_noun);
+
   /** Tier 6.
   **/
     u3_noun u3wf_bull(u3_noun);