From fcedfddf00b3f994e4f4e40332ac7fc192c63244 Mon Sep 17 00:00:00 2001
From: polwex <polwex@sortug.com>
Date: Sun, 5 Oct 2025 21:56:51 +0700
Subject: claude is gud

---
 vere/pkg/noun/jets/c/rep.c | 199 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 199 insertions(+)
 create mode 100644 vere/pkg/noun/jets/c/rep.c

(limited to 'vere/pkg/noun/jets/c/rep.c')

diff --git a/vere/pkg/noun/jets/c/rep.c b/vere/pkg/noun/jets/c/rep.c
new file mode 100644
index 0000000..914e917
--- /dev/null
+++ b/vere/pkg/noun/jets/c/rep.c
@@ -0,0 +1,199 @@
+/// @file
+
+#include "jets/k.h"
+#include "jets/q.h"
+#include "jets/w.h"
+
+#include "noun.h"
+
+/*
+  Get the lowest `n` bits of a word `w` using a bitmask.
+*/
+#define TAKEBITS(n,w) \
+  ((n)==32) ? (w) :   \
+  ((n)==0)  ? 0   :   \
+  ((w) & ((1 << (n)) - 1))
+
+/*
+  Divide, rounding up.
+*/
+#define DIVCEIL(x,y) \
+  (x==0) ? 0 :       \
+  1 + ((x - 1) / y);
+
+static u3_noun
+_bit_rep(u3_atom bits, u3_noun blox)
+{
+  if ( (c3n == u3a_is_cat(bits) || bits==0 || bits>31) ) {
+    return u3m_bail(c3__fail);
+  }
+
+  //
+  //  Calculate input and output size.
+  //
+  c3_w num_blox_w = u3qb_lent(blox);
+  c3_w bit_widt_w = num_blox_w * bits;
+  c3_w wor_widt_w = DIVCEIL(bit_widt_w, 32);
+  u3i_slab  sab_u;
+  u3i_slab_bare(&sab_u, 5, wor_widt_w);
+
+  //
+  //  Fill the atom buffer with bits from each block.
+  //
+  //  Bits are pushed into the `acc_w` register and flushed to the buffer
+  //  once full.
+  //
+  //  acc_w  register
+  //  use_w  number of register bits filled (used)
+  //  cur_w  next buffer word to flush into.
+  //
+  {
+    c3_w acc_w=0, use_w=0, *cur_w=sab_u.buf_w;
+
+#   define FLUSH() *cur_w++=acc_w; acc_w=use_w=0
+#   define SLICE(sz,off,val) TAKEBITS(sz, val) << off
+
+    for (c3_w i=0; i<num_blox_w; i++) {
+      u3_noun blok_n = u3h(blox);
+      blox = u3t(blox);
+
+      if ( c3n == u3a_is_cat(blok_n) ) {
+        return u3m_bail(c3__fail);
+      }
+
+      c3_w blok_w = blok_n;
+
+      for (c3_w rem_in_blok_w=bits; rem_in_blok_w;) {
+        c3_w rem_in_acc_w = 32 - use_w;
+        if (rem_in_blok_w == rem_in_acc_w) {              //  EQ
+          acc_w |= SLICE(rem_in_blok_w, use_w, blok_w);
+          FLUSH();
+          rem_in_blok_w = 0;
+        }
+        else if (rem_in_blok_w < rem_in_acc_w) {          //  LT
+          acc_w |= SLICE(rem_in_blok_w, use_w, blok_w);
+          use_w += rem_in_blok_w;
+          rem_in_blok_w = 0;
+        }
+        else {                                            //  GT
+          acc_w |= SLICE(rem_in_acc_w, use_w, blok_w);
+          rem_in_blok_w -= rem_in_acc_w;
+          blok_w = blok_w >> rem_in_acc_w;
+          FLUSH();
+        }
+      }
+    }
+
+    //
+    //  If the last word isn't fully used, it will still need to be
+    //  flushed.
+    //
+    if (use_w) {
+      FLUSH();
+    }
+  }
+
+  return u3i_slab_mint(&sab_u);
+}
+
+static u3_noun
+_block_rep(u3_atom a,
+           u3_noun b)
+{
+  if ( !_(u3a_is_cat(a)) || (a >= 32) ) {
+    return u3m_bail(c3__fail);
+  }
+  else {
+    c3_g       a_g = a;
+    c3_w     tot_w = 0;
+    u3i_slab sab_u;
+
+    /* Measure and validate the slab required.
+    */
+    {
+      u3_noun cab = b;
+
+      while ( 1 ) {
+        u3_noun h_cab;
+        c3_w    len_w;
+
+        if ( 0 == cab ) {
+          break;
+        }
+        else if ( c3n == u3du(cab) ) {
+          return u3m_bail(c3__exit);
+        }
+        else if ( c3n == u3ud(h_cab = u3h(cab)) ) {
+          return u3m_bail(c3__exit);
+        }
+        else if ( (tot_w + (len_w = u3r_met(a_g, h_cab))) < tot_w ) {
+          return u3m_bail(c3__fail);
+        }
+        tot_w++;
+        cab = u3t(cab);
+      }
+
+      if ( 0 == tot_w ) {
+        return 0;
+      }
+
+      u3i_slab_init(&sab_u, a_g, tot_w);
+    }
+
+    /* Chop the list atoms in.
+    */
+    {
+      u3_noun cab = b;
+      c3_w  pos_w = 0;
+
+      while ( 0 != cab ) {
+        u3_noun h_cab = u3h(cab);
+
+        u3r_chop(a_g, 0, 1, pos_w, sab_u.buf_w, h_cab);
+        pos_w++;
+        cab = u3t(cab);
+      }
+    }
+
+    return u3i_slab_mint(&sab_u);
+  }
+}
+
+u3_noun
+u3qc_rep(u3_atom a,
+         u3_atom b,
+         u3_noun c)
+{
+  if ( 1 == b ) {
+    return _block_rep(a, c);
+  }
+
+  if ( 0 == a ) {
+    return _bit_rep(b, c);
+  }
+
+  u3l_log("rep: stub");
+  return u3_none;
+}
+
+u3_noun
+u3wc_rep(u3_noun cor)
+{
+  u3_atom bloq, step;
+  u3_noun a, b;
+  u3x_mean(cor, u3x_sam_2, &a,
+                u3x_sam_3, &b, 0);
+  u3x_bite(a, &bloq, &step);
+
+  return u3qc_rep(bloq, step, b);
+}
+
+u3_noun
+u3kc_rep(u3_atom a,
+         u3_atom b,
+         u3_noun c)
+{
+  u3_noun res = u3qc_rep(a, b, c);
+  u3z(a); u3z(b); u3z(c);
+  return res;
+}
-- 
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