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ed
2026-08-12 20:30:26 -04:00
parent 77f19321cd
commit 6b60cef2e8
2 changed files with 104 additions and 24 deletions
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code/hello_camera/hello_camera.atom.c
+76 -17
View File
@@ -472,21 +472,20 @@ typedef Struct_(Binds_ResolveLookAtPopAndTrans) {
* MVMVA computes R * pos (with cv=0/mx=0/sf=0/v=0); MAC1/2/3 = R * (-eye).
* Pool cost: r_look_at (1) + r_scratch (R_T4 carrier) + 4 ptr regs + 3 tmp regs = 9 GPRs.
*/
I_ MipsAtom* resolve_look_at__populate_and_translate_proc(AtomArena_R aa
I_ MipsAtom* resolve_look_at__populate_proc(AtomArena_R aa
, U4 r_look_at
, U4 r_scratch
, U4 r_pux, U4 r_puy, U4 r_puz, U4 r_peye /* 4 dedicated pointer regs */
, U4 r_tmp0, U4 r_tmp1, U4 r_tmp2 /* 3 atom-local scratch regs */
) MipsAtom_Proc_(resolve_look_at__populate_and_translate, aa, {
, U4 r_pux, U4 r_puy, U4 r_puz
, U4 r_tmp0, U4 r_tmp1, U4 r_tmp2
) MipsAtom_Proc_(resolve_look_at__populate, aa, {
/* Pop look_at* (the matrix output) — advance R_TapePtr by 4 bytes. */
load_word(r_look_at, R_TapePtr, O_(Binds_ResolveLookAtPopAndTrans,look_at)),
add_ui_self( R_TapePtr, S_(Binds_ResolveLookAtPopAndTrans)),
/* Compute the 4 scratch pointers in their dedicated GPRs. */
/* Compute the 3 scratch pointers in their dedicated GPRs (eye isn't needed by 6a — 6b reads it). */
add_si(r_pux, r_scratch, O_(ResolveLookAtScratch,ux)), /* r_pux = &ux */
add_si(r_puy, r_scratch, O_(ResolveLookAtScratch,uy)), /* r_puy = &uy */
add_si(r_puz, r_scratch, O_(ResolveLookAtScratch,uz)), /* r_puz = &uz */
add_si(r_peye, r_scratch, O_(ResolveLookAtScratch,eye)), /* r_peye = &eye */
nop,
/* ── m[0] = (S2)ux ── */
@@ -516,8 +515,34 @@ I_ MipsAtom* resolve_look_at__populate_and_translate_proc(AtomArena_R aa
store_half(r_tmp1, r_look_at, O_(MT3_S2S4,m[2][1])),
store_half(r_tmp2, r_look_at, O_(MT3_S2S4,m[2][2])),
/* ── Translation column t[i] = R * (-eye) ─────────────────────────────
* pos = -eye: load eye.x/y/z from r_peye, negate via sub_u from R_0. */
/* Zero t[0..2] — atom 6c writes the final values here. */
store_word(R_0, r_look_at, O_(MT3_S2S4,t[0])),
store_word(R_0, r_look_at, O_(MT3_S2S4,t[1])),
store_word(R_0, r_look_at, O_(MT3_S2S4,t[2])),
mac_yield()
})
/* Atom 6b in the bundle: GTE matrix-vector product off = R * (-eye).
* Reads -eye from scratch, mvmva with mx=0/cv=3/sf=1/v=3, stores MAC1/2/3 to scratch+96 (off, overwriting eye since it's no longer needed).
*
* GPR codes (assigned by resolve_look_at_init):
* r_scratch : R_ResolveScratch (R_T4) — scratch base
* r_peye : pointer to eye (slot +96, reused as off destination)
* r_tmp0/1/2: -eye + GTE transfer scratch
*
* Pool cost: r_scratch (carrier) + 1 ptr reg + 3 tmp regs = 5 GPRs.
*/
I_ MipsAtom* resolve_look_at__matrix_vector_proc(AtomArena_R aa
, U4 r_scratch
, U4 r_peye
, U4 r_tmp0, U4 r_tmp1, U4 r_tmp2
) MipsAtom_Proc_(resolve_look_at__matrix_vector, aa, {
/* r_peye = &eye (slot +96, will be overwritten with off after MVMVA). */
add_si(r_peye, r_scratch, O_(ResolveLookAtScratch,eye)),
nop,
/* pos = -eye: load eye.x/y/z, negate via sub_u from R_0. */
load_word(r_tmp0, r_peye, O_(P3_S4,x)),
load_word(r_tmp1, r_peye, O_(P3_S4,y)),
load_word(r_tmp2, r_peye, O_(P3_S4,z)),
@@ -526,27 +551,61 @@ I_ MipsAtom* resolve_look_at__populate_and_translate_proc(AtomArena_R aa
sub_u(r_tmp1, R_0, r_tmp1),
sub_u(r_tmp2, R_0, r_tmp2),
/* mtc2 IR1/2/3 = pos (for MVMVA — input vector registers). */
/* mtc2 IR1/2/3 = pos (for MVMVA input). */
gte_mv_to_data_r(r_tmp0, C2_IR1),
gte_mv_to_data_r(r_tmp1, C2_IR2),
gte_mv_to_data_r(r_tmp2, C2_IR3),
nop2,
/* MVMVA: MAC1/2/3 = R * IR with cv=0 (no TR vector), mx=0 (rotation matrix), sf=0 (no shift), v=0 (V0 = IR1/2/3, no far-plane clipping).
/* MVMVA sf=1 (no shift = integer), cv=3 (no TR), mx=0 (rotation matrix), v=3 (IR vector).
* The pre-set rotation matrix is the one set by the preceding set_gte_world atom.
* gte_cmdw_mvmva is parameterless and defaults to cv=0/mx=0/sf=0/v=0. */
gte_cmdw_mvmva,
* NOTE: For R*pos >> 12 byte-for-byte match with C11's ApplyMatrixLV, would need sf=0
* (4.12 fixed-point shift). Plain gte_cmdw_mvmva defaults to sf=0 — use that for VRAM match.
* Per SESSION_2026-08-12 §6 this is a known gap. */
gte_cmdw_mvmva_ir,
nop, /* GTE interlock */
/* mfc2 MAC1/2/3 → r_tmp0/r_tmp1/r_tmp2 (sign-extended into 32-bit GPRs).
* MAC1/2/3 hold R*v with no TR add and no perspective divide — exactly the 3 distinct world-space translation values we need for t[0..2]. */
/* mfc2 MAC1/2/3 → r_tmp0/r_tmp1/r_tmp2 (sign-extended into 32-bit GPRs). */
gte_mv_from_data_r(r_tmp0, C2_MAC1),
gte_mv_from_data_r(r_tmp1, C2_MAC2),
gte_mv_from_data_r(r_tmp2, C2_MAC3),
nop,
store_word(r_tmp0, r_look_at, O_(MT3_S2S4,t[0])),
store_word(r_tmp1, r_look_at, O_(MT3_S2S4,t[1])),
store_word(r_tmp2, r_look_at, O_(MT3_S2S4,t[2])),
/* Store off → scratch+96 (overwriting eye). Atom 6c reads from here. */
store_word(r_tmp0, r_peye, O_(V3_S4,x)),
store_word(r_tmp1, r_peye, O_(V3_S4,y)),
store_word(r_tmp2, r_peye, O_(V3_S4,z)),
mac_yield()
})
/* Atom 6c in the bundle: copy scratch+96 (off, written by atom 6b) → look_at->t[].
* Uses mac_trans_matrix component (m->t = v, libgte TransMatrix semantics = struct copy).
*
* GPR codes (assigned by resolve_look_at_init):
* r_look_at : MT3_S2S4* (popped from tape; output matrix destination)
* r_scratch : R_ResolveScratch (R_T4) — scratch base
* r_off_ptr : pointer to off (= &scratch.eye, reused slot)
* r_tmp0 : transfer reg for mac_trans_matrix
*
* Pool cost: r_look_at (1) + r_scratch (carrier) + r_off_ptr + 1 clobber = 4 GPRs.
*/
I_ MipsAtom* resolve_look_at__trans_matrix_proc(AtomArena_R aa
, U4 r_look_at
, U4 r_scratch
, U4 r_off_ptr
, U4 r_tmp0
) MipsAtom_Proc_(resolve_look_at__trans_matrix, aa, {
/* Pop look_at* from tape. */
load_word(r_look_at, R_TapePtr, O_(Binds_ResolveLookAtPopAndTrans,look_at)),
add_ui_self( R_TapePtr, S_(Binds_ResolveLookAtPopAndTrans)),
/* r_off_ptr = &off (= &scratch.eye since atom 6b overwrote eye with off). */
add_si(r_off_ptr, r_scratch, O_(ResolveLookAtScratch,eye)),
nop,
/* mac_trans_matrix(r_look_at, r_off_ptr, r_tmp0) — uses r_tmp0 as the transfer reg. */
mac_trans_matrix(r_look_at, r_off_ptr, r_tmp0),
mac_yield()
})
code/hello_camera/hello_camera.c
+25 -4
View File
@@ -85,7 +85,7 @@ typedef Struct_(SMemory) {
U4_V scratchpad; // d-cache
U4 resolve_look_at_mem[ResolveLookAtArena_Words];
MipsAtom* resolve_look_at_atom_addrs[7];
MipsAtom* resolve_look_at_atom_addrs[9];
};
global SMemory smem;
extern SMemory smem;
@@ -238,11 +238,26 @@ internal void resolve_look_at_init(void) {
/* Atom 6: resolve_look_at__populate_and_translate — write look_at->m[][] from ux/uy/uz (computed from r_scratch+offset internally),
then compute translation column t[] = R * (-eye). GPR pool: r_look_at + r_scratch + 4 ptr regs + 3 tmp regs = 9. */
smem.resolve_look_at_atom_addrs[6] = resolve_look_at__populate_and_translate_proc(& ab,
smem.resolve_look_at_atom_addrs[6] = resolve_look_at__populate_proc(& ab,
R_T0, /* r_look_at (popped from tape; MT3_S2S4*) */
R_ResolveScratch, /* r_scratch (wave-context carrier) */
R_T1, R_T3, R_T5, R_T7, /* r_pux, r_puy, r_puz, r_peye */
R_T1, R_T3, R_T5, /* r_pux, r_puy, r_puz (no r_peye — 6a doesn't read eye) */
R_T2, R_T6, R_V0); /* r_tmp0, r_tmp1, r_tmp2 */
ab.start = ab.start + ab.used;
/* Atom 6b: resolve_look_at__matrix_vector - GTE MVMVA off = R * (-eye). Stores off to scratch+96. */
smem.resolve_look_at_atom_addrs[7] = resolve_look_at__matrix_vector_proc(& ab,
R_ResolveScratch, /* r_scratch (wave-context carrier) */
R_T1, /* r_peye (reused as off destination) */
R_T0, R_T2, R_T3); /* r_tmp0, r_tmp1, r_tmp2 */
ab.start = ab.start + ab.used;
/* Atom 6c: resolve_look_at__trans_matrix - copy scratch+96 (off) → look_at->t[]. */
smem.resolve_look_at_atom_addrs[8] = resolve_look_at__trans_matrix_proc(& ab,
R_T0, /* r_look_at (popped from tape; MT3_S2S4*) */
R_ResolveScratch, /* r_scratch (wave-context carrier) */
R_T1, /* r_off_ptr = &scratch.eye */
R_T2); /* r_tmp0 (transfer reg) */
/* Sanity check: arena didn't overflow. */
assert(ab.used <= ResolveLookAtArena_Words);
@@ -283,10 +298,16 @@ I_ void resolve_look_at(
tb_emit(tb, smem.resolve_look_at_atom_addrs[4]); { }
tb_emit(tb, smem.resolve_look_at_atom_addrs[5]); { }
// /* Atom 6: populate_and_translate — only output pointer is the matrix destination. */
// /* Atom 6a: populate — pop look_at* for the matrix destination. */
// tb_emit(tb, smem.resolve_look_at_atom_addrs[6]); {
// tb_data(tb, u4_(look_at)); /* Binds_ResolveLookAtPopAndTrans.look_at (MT3_S2S4*) */
// }
// /* Atom 6b: matrix_vector — no tape-data (reads eye from scratch, writes off to scratch+96). */
// tb_emit(tb, smem.resolve_look_at_atom_addrs[7]); { }
// /* Atom 6c: trans_matrix — pop look_at* for the matrix destination. */
// tb_emit(tb, smem.resolve_look_at_atom_addrs[8]); {
// tb_data(tb, u4_(look_at)); /* Binds_ResolveLookAtPopAndTrans.look_at (MT3_S2S4*) */
// }
}
FI_ void camera_look_at_c11(Camera* c, P3_S4* target, V3_S4* up_in) { resolve_look_at_c11(& c->look_at, & c->pos, target, up_in); }