claude is gud

1 files changed, 192 insertions, 0 deletions

diff --git a/vere/pkg/noun/jets/c/rip.c b/vere/pkg/noun/jets/c/rip.c
new file mode 100644
index 0000000..bff23b8
--- /dev/null
+++ b/vere/pkg/noun/jets/c/rip.c
@@ -0,0 +1,192 @@
+/// @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);
+
+/*
+  `ripn` breaks `atom` into a list of blocks, of bit-width `bits`. The
+  resulting list will be least-significant block first.
+
+  XX TODO This only handles cases where the bit-width is <= 32.
+
+  For each block we produce, we need to grab the relevant words inside
+  `atom`, so we first compute their indicies.
+
+  `ins_idx` is the word-index of the least-significant word we
+  care about, and `sig_idx` is the word after that.
+
+  Next we grab those words (`ins_word` and `sig_word`) from the atom
+  using `u3r_word`. Note that `sig_idx` might be out-of-bounds for the
+  underlying array of `atom`, but `u3r_word` returns 0 in that case,
+  which is exatly what we want.
+
+  Now, we need to grab the relevant bits out of both words, and combine
+  them. `bits_rem_in_ins_word` is the number of remaining (insignificant)
+  bits in `ins_word`, `nbits_ins` is the number of bits we want from the
+  less-significant word, and `nbits_sig` from the more-significant one.
+
+  Take the least significant `nbits_sig` bits from `sig_word`, and take
+  the slice we care about from `ins_word`. In order to take that slice,
+  we drop `bits_rem_in_ins_word` insignificant bits, and then take the
+  `nbits_sig` most-significant bits.
+
+  Last, we slice out those bits from the two words, combine them into
+  one word, and cons them onto the front of the result.
+*/
+static u3_noun
+_bit_rip(u3_atom bits, u3_atom atom)
+{
+  if ( !_(u3a_is_cat(bits) || bits==0 || bits>31) ) {
+    return u3m_bail(c3__fail);
+  }
+
+  c3_w bit_width  = u3r_met(0, atom);
+  c3_w num_blocks = DIVCEIL(bit_width, bits);
+
+  u3_noun res = u3_nul;
+
+  for ( c3_w blk = 0; blk < num_blocks; blk++ ) {
+    c3_w next_blk = blk + 1;
+    c3_w blks_rem = num_blocks - next_blk;
+    c3_w bits_rem = blks_rem * bits;
+    c3_w ins_idx  = bits_rem / 32;
+    c3_w sig_idx  = ins_idx + 1;
+
+    c3_w bits_rem_in_ins_word = bits_rem % 32;
+
+    c3_w ins_word  = u3r_word(ins_idx, atom);
+    c3_w sig_word  = u3r_word(sig_idx, atom);
+    c3_w nbits_ins = c3_min(bits, 32 - bits_rem_in_ins_word);
+    c3_w nbits_sig = bits - nbits_ins;
+
+    c3_w ins_word_bits = TAKEBITS(nbits_ins, ins_word >> bits_rem_in_ins_word);
+    c3_w sig_word_bits = TAKEBITS(nbits_sig, sig_word);
+
+    c3_w item = ins_word_bits | (sig_word_bits << nbits_ins);
+
+    res = u3nc(item, res);
+  }
+
+  return res;
+}
+
+static u3_noun
+_block_rip(u3_atom bloq, u3_atom b)
+{
+  if ( !_(u3a_is_cat(bloq)) || (bloq >= 32) ) {
+    return u3m_bail(c3__fail);
+  }
+
+  c3_g bloq_g = bloq;
+
+  /*
+    This is a fast-path for the case where all the resulting blocks will
+    fit in 31-bit direct atoms.
+  */
+  if ( bloq_g < 5 ) {                                   //  produce direct atoms
+    u3_noun acc     = u3_nul;
+
+    c3_w met_w   = u3r_met(bloq_g, b);                  //  num blocks in atom
+    c3_w nbits_w = 1 << bloq_g;                         //  block size in bits
+    c3_w bmask_w = (1 << nbits_w) - 1;                  //  result mask
+
+    for ( c3_w i_w = 0; i_w < met_w; i_w++ ) {          //  `i_w` is block index
+      c3_w nex_w = i_w + 1;                             //  next block
+      c3_w pat_w = met_w - nex_w;                       //  blks left after this
+      c3_w bit_w = pat_w << bloq_g;                     //  bits left after this
+      c3_w wor_w = bit_w >> 5;                          //  wrds left after this
+      c3_w sif_w = bit_w & 31;                          //  bits left in word
+      c3_w src_w = u3r_word(wor_w, b);                  //  find word by index
+      c3_w rip_w = (src_w >> sif_w) & bmask_w;          //  get item from word
+
+      acc = u3nc(rip_w, acc);
+    }
+
+    return acc;
+  }
+
+  u3_noun acc   = u3_nul;
+  c3_w    met_w = u3r_met(bloq_g, b);
+  c3_w    len_w = u3r_met(5, b);
+  c3_g    san_g = (bloq_g - 5);
+  c3_w    san_w = 1 << san_g;
+  c3_w    dif_w = (met_w << san_g) - len_w;
+  c3_w    tub_w = ((dif_w == 0) ? san_w : (san_w - dif_w));
+
+  for ( c3_w i_w = 0; i_w < met_w; i_w++ ) {
+    c3_w     pat_w = (met_w - (i_w + 1));
+    c3_w     wut_w = (pat_w << san_g);
+    c3_w     sap_w = ((0 == i_w) ? tub_w : san_w);
+    c3_w       j_w;
+    u3_atom    rip;
+    u3i_slab sab_u;
+    u3i_slab_bare(&sab_u, 5, sap_w);
+
+    for ( j_w = 0; j_w < sap_w; j_w++ ) {
+      sab_u.buf_w[j_w] = u3r_word(wut_w + j_w, b);
+    }
+
+    rip = u3i_slab_mint(&sab_u);
+    acc = u3nc(rip, acc);
+    len_w -= san_w;
+  }
+
+  return acc;
+}
+
+u3_noun
+u3qc_rip(u3_atom a,
+         u3_atom b,
+         u3_atom c)
+{
+  if ( 1 == b ) {
+    return _block_rip(a, c);
+  }
+
+  if ( 0 == a ) {
+    return _bit_rip(b, c);
+  }
+
+  u3l_log("rip: stub");
+  return u3_none;
+}
+
+u3_noun
+u3wc_rip(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_rip(bloq, step, u3x_atom(b));
+}
+
+u3_noun
+u3kc_rip(u3_atom a,
+         u3_atom b,
+         u3_atom c)
+{
+  u3_noun pro = u3qc_rip(a, b, c);
+  u3z(a); u3z(b); u3z(c);
+  return pro;
+}