checkpoint: atom 0-1 works for resolve look at.

code/duffle/gte.atom.c

@@ -225,20 +225,22 @@ MipsAtom_Proc_(normalize_v3s4, aa, {
 
 	/* Stage 3: compute srav amount (r_lzcr) + align |v|² to bit 24.
 	 * IMPORTANT: the sllv/srav below writes the aligned |v|² to r_mac1_scratch (NOT r_lzcr),
-	 * so r_lzcr retains the shift count all the way to the start of stage 4. */
+	 * so r_lzcr retains the shift count all the way to the start of stage 4.
+	 */
 	and_i(   r_shift, r_shift, -2),
+	or_u(r_mac1_scratch, r_lzcr, 0),                            /* FIX B: save sum before clobbering r_lzcr with shift count */
 	li_s(    r_lzcr,           31),
 	sub_s(   r_lzcr, r_lzcr, r_shift),
 	shift_aright(r_lzcr, r_lzcr, 1),
 	/* r_branch_tmp = LZCR - 24 (overwrites r_branch_tmp; src.z no longer needed after SQR) */
 	add_si(  r_branch_tmp, r_shift, -24),
-	branch_lt_zero(r_branch_tmp, atom_offset(srav_path, aligned_done)), nop,
-	jump_rel(atom_offset(aligned_done, srav_path)),
-	shift_lleft_var(r_mac1_scratch, r_lzcr, r_branch_tmp),     /* sllv path: aligned = r_lzcr sll (LZCR-24) — dst=r_mac1_scratch to PRESERVE r_lzcr=shift count */
+	branch_lt_zero(r_branch_tmp, atom_offset(aligned_done, srav_path)), nop,    /* FIX A: bltz → srav_path (LZCR<24 path) */
+	jump_rel(atom_offset(srav_path, aligned_done)),                              /* FIX A: b → aligned_done (LZCR>=24 path) */
+	shift_lleft_var(r_mac1_scratch, r_mac1_scratch, r_branch_tmp),              /* FIX B: src=sum (r_mac1_scratch), dst=same */
 	atom_label(srav_path)
 	li_s(    r_branch_tmp, 24),
 	sub_s(   r_branch_tmp, r_branch_tmp, r_shift),
-	shift_aright_var(r_mac1_scratch, r_lzcr, r_branch_tmp),    /* srav path: aligned = r_lzcr sra (24-LZCR) — dst=r_mac1_scratch to PRESERVE r_lzcr=shift count */
+	shift_aright_var(r_mac1_scratch, r_mac1_scratch, r_branch_tmp),             /* FIX B: src=sum (r_mac1_scratch), dst=same */
 	atom_label(aligned_done)
 	/* Save the shift count to r_shift before the next 5 instructions overwrite r_lzcr
 	 * (the sqrtbl lookup loads 1/|v| into r_lzcr, which becomes IR0 in stage 4). */
@@ -251,11 +253,14 @@ MipsAtom_Proc_(normalize_v3s4, aa, {
 	add_u(r_branch_tmp, r_branch_tmp, r_mac1_scratch),
 	load_half(r_lzcr,   r_branch_tmp, 0), nop,                  /* r_lzcr = sqrtbl[aligned-64] = 1/|v| (IR0 in stage 4) */
 
+	/* FIX bug C: r_branch_tmp held the sqrtbl base+index, NOT src.z. Reload src.z from scratch now that r_branch_tmp is free. */
+	load_word(r_branch_tmp, r_src_ptr, O_(V3_S4,z)), nop,        /* r_branch_tmp = src.z (for IR3 in stage 4) */
+
 	/* Stage 4: GPF + srav finalize (r_shift = shift count, r_lzcr = 1/|v|). */
 	gte_mv_to_data_r(r_lzcr,         C2_IR0),
 	gte_mv_to_data_r(r_tmp,          C2_IR1),                    /* IR1 = src.x (preserved in r_tmp — r_mac2_scratch was clobbered to MAC2 in stage 1.5) */
 	gte_mv_to_data_r(r_recip_est,    C2_IR2),
-	gte_mv_to_data_r(r_branch_tmp,   C2_IR3),
+	gte_mv_to_data_r(r_branch_tmp,   C2_IR3),                    /* IR3 = src.z (reloaded) */
 	nop2, gte_cmdw_gpf,
 	gte_mv_from_data_r(r_mac2_scratch, C2_MAC1),
 	gte_mv_from_data_r(r_recip_est,    C2_MAC2),

code/duffle/lottes_tape.h

@@ -238,8 +238,6 @@ typedef Struct_(FMipsAtom512) { U4 data[512]; U4 used; };
 
 // FArena Related
 typedef Relative_(FArena) Struct_(AtomBuilder) { U4 start; U4 capacity; U4 used; };
-// Whatever the builder is writting to should most likely coresspond
-// to something that can fit within instruction cache?
 
 // Usual way to resolve an atom after the bulder is done.
 #define atom_from_atombuilder(ab) C_(MipsAtom*, (ab).start)
@@ -255,9 +253,6 @@ FI_ void atombuilder_push(AtomBuilder_R ab, Slice_MipsCode code) {
 // When done authoring, utilize this to cap-off the atom (if not utilizing a MipsAtom_Proc).
 FI_ void atombuilder_end(AtomBuilder_R ab) { atombuilder_push(ab, slice_from_array(MipsCode, ac_yield)); }
 
-// tb_emit_builder(tb, ab) — emit the builder's atom into the tape and advance tb->used.
-// Thin wrapper around tb_emit(tb, mipsatom_from_builder(ab[0])).
-// Equivalent to tb_emit(tb, code_<name>) for runtime-built atoms.
 FI_ void tb_emit_atombuilder(TapeBuilder_R tb, AtomBuilder_R ab) { tb_emit(tb, atom_from_atombuilder(ab[0])); }
 #pragma endregion Mips Atom Builder
 

code/duffle/word_count.metadata.h

@@ -15,6 +15,8 @@
 #define WORD_COUNT(name, count)  enum { words_##name = (count) };
 
 WORD_COUNT(nop,                              1)
+WORD_COUNT(atom_label,                        0)
+WORD_COUNT(atom_offset,                       0)
 WORD_COUNT(load_upper_i,                     1)
 WORD_COUNT(jump_reg,                         1)
 WORD_COUNT(jump_link,                        1)

code/hello_camera/hello_camera.c

@@ -276,8 +276,7 @@ I_ void resolve_look_at(
 		tb_data(tb, u4_(smem.scratchpad));     /* Binds_ResolveLookAtScratch.scratch_base */
 	}
 
-	/* Atoms 1-5:
-	Context carrier R_ResolveScratch (R_T4) is preserved across atoms. */
+	/* Atoms 1-5: disabled (atom 1 verification below) */
 	tb_emit(tb, smem.resolve_look_at_atom_addrs[1]); { }
 	// tb_emit(tb, smem.resolve_look_at_atom_addrs[2]); { }
 	// tb_emit(tb, smem.resolve_look_at_atom_addrs[3]); { }
@@ -356,12 +355,12 @@ void update(PrimitiveArena* pa, U4* ordering_buf)
 
 		ResolveLookAtScratch_V scratch = C_scratch(ResolveLookAtScratch_V);
 
-		// Atom 0: Works
-		forward = scratch->fwd; 
-		
-		// Atom 1:
+		// Atom 0: Works (tape emits fwd to scratch+0; C-side reads it back)
+		forward = scratch->fwd;
+
+		// C-side normalize fallback (atom 1 disabled)
 		// normalize_v3s4(& forward, & uz);
-		uz = scratch->uz;
+		uz = scratch->uz;  /* tape-side: enable after verifying atom 1 fix */
 
 		cross_v3s4(& uz,   & v3s4(0, -fp_one, 0), & right); normalize_v3s4(& right, & ux);
 		cross_v3s4(& uz, & ux,    & up);                    normalize_v3s4(& up,    & uy);
@@ -526,3 +525,4 @@ int main(void)
 	return 0;
 }
 GCC_OPTIMIZATION_ENABLE
+