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Moving definitions to use dedicated scratch register.

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ed
2026-08-18 09:26:49 -04:00
parent da007d342e
commit 86fe189b4e
5 changed files with 108 additions and 67 deletions
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code/hello_camera/hello_camera.atom.c
+32 -45
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@@ -111,66 +111,59 @@ typedef AtomBundle_(resolve_look_at) { MipsAtom
*pop_mv_trans;
};
enum {
// TODO(Ed): We can resolve scratch at anytime its fixed to a specific address.
R_ResolveScratch = R_T4 atom_reg atom_type(U4*),
#define R_ResolveScratch_Code R_T4_Code
typedef Struct_(ResolveLookAtScratch) {
V3_S4 fwd;
V3_S4 uz;
V3_S4 right;
V3_S4 ux;
V3_S4 up;
V3_S4 uy;
P3_S4 eye;
P3_S4 target;
V3_S4 up_in;
};
/* Binds_ResolveLookAtSub — what the C side pushes onto the tape before input_and_sub.
* The scratchpad base is no longer pushed because R_ScratchBase (= R_SP) is a tape carrier
* preserved across atoms; the atom body reads 0x1F800000 directly from R_SP. */
typedef Struct_(Binds_ResolveLookAt) {
MT3_S2S4* look_at;
P3_S4* eye;
P3_S4* target;
V3_S4* up_in;
};
/* ─── ResolveLookAtScratch — offset schema for the resolve_look_at bundle's */
typedef Struct_(ResolveLookAtScratch) {
V3_S4 fwd; /* offset +0 (16 bytes — 4 S4 fields incl. internal pad) */
V3_S4 uz; /* offset +16 (16 bytes) */
V3_S4 right; /* offset +32 (16 bytes) */
V3_S4 ux; /* offset +48 (16 bytes) */
V3_S4 up; /* offset +64 (16 bytes) */
V3_S4 uy; /* offset +80 (16 bytes) */
P3_S4 eye; /* offset +96 (16 bytes; storage alias of V3_S4) */
P3_S4 target; /* offset +112 (16 bytes; storage alias of V3_S4) */
V3_S4 up_in; /* offset +128 (16 bytes) */
};
typedef Struct_(Binds_ResolveLookAtSub) {
P3_S4* target;
P3_S4* eye;
P3_S4* eye;
V3_S4* up_in;
ResolveLookAtScratch* scratchpad;
};
typedef Struct_(RegUse_resolve_look_at_input_and_sub) {
Reg scratch;
Reg target; Reg eye; Reg up_in;
Reg t0; Reg t1; Reg t2; Reg t3; Reg t4;
};
/* Atom 0 in the bundle: input_and_sub. Stages C-side inputs into the scratchpad and computes fwd = target - eye. */
internal MipsAtom* AtomBundleEntry_(resolve_look_at,input_and_sub)(AtomArena_R aa, RegUse_resolve_look_at_input_and_sub r)
internal MipsAtom* AtomBundleEntry_(resolve_look_at,input_and_sub)(AtomArena_R aa, RegUse_resolve_look_at_input_and_sub r)
atom_info(atom_bind(Binds_ResolveLookAtSub)) MipsAtom_Proc_(aa, {
load_word(r.target, R_TapePtr, O_(Binds_ResolveLookAtSub,target)),
load_word(r.eye, R_TapePtr, O_(Binds_ResolveLookAtSub,eye)),
load_word(r.up_in, R_TapePtr, O_(Binds_ResolveLookAtSub,up_in)),
load_word(r.scratch, R_TapePtr, O_(Binds_ResolveLookAtSub,scratchpad)),
LdSlot_ add_ui_self( R_TapePtr, S_(Binds_ResolveLookAtSub)),
load_word(r.target, R_TapePtr, O_(Binds_ResolveLookAtSub,target)),
load_word(r.eye, R_TapePtr, O_(Binds_ResolveLookAtSub,eye)),
load_word(r.up_in, R_TapePtr, O_(Binds_ResolveLookAtSub,up_in)),
LdSlot_ add_ui_self(R_TapePtr, S_(Binds_ResolveLookAtSub)),
/* Stage up_in.x/y/z into the scratchpad. */
/* Stage up_in.x/y/z into the scratchpad. R_ScratchBase = R_SP = 0x1F800000. */
mac_load_word_v3( r.t0, r.t1, r.t2, r.up_in, 0), LdSlot_
mac_store_word_v3(r.t0, r.t1, r.t2, r.scratch, O_(ResolveLookAtScratch,up_in)),
mac_store_word_v3(r.t0, r.t1, r.t2, R_ScratchBase, O_(ResolveLookAtScratch,up_in)),
// Stage eye.x/y/z into the scratchpad (atom 6 reads these for the translation column).
mac_load_word_v3( r.t0, r.t1, r.t2, r.eye, 0), LdSlot_
mac_store_word_v3(r.t0, r.t1, r.t2, r.scratch, O_(ResolveLookAtScratch,eye)),
mac_store_word_v3(r.t0, r.t1, r.t2, R_ScratchBase, O_(ResolveLookAtScratch,eye)),
/* Compute fwd = target - eye. */
// mac_load_p3s4(t3, R_AT, t4, r.eye, 0),
mac_load_word_v3(r.t3, R_AT, r.t4, r.target, 0), LdSlot_
mac_load_word_v3(r.t3, R_AT, r.t4, r.target, 0), LdSlot_
mac_sub_s_v3_self(
r.t3, R_AT, r.t4,
r.t0, r.t1, r.t2),
mac_store_word_v3(r.t3, R_AT, r.t4, r.scratch, O_(ResolveLookAtScratch,fwd)),
mac_store_word_v3(r.t3, R_AT, r.t4, R_ScratchBase, O_(ResolveLookAtScratch,fwd)),
mac_yield()
})
@@ -180,8 +173,6 @@ typedef Struct_(Binds_ResolveLookAtPopMvTrans) {
U4 look_at; /* MT3_S2S4* — destination matrix address */
};
typedef Struct_(RegUse_resolve_look_at__pop_mv_trans) {
Reg scratch; /* loaded via load_word_imm below — can't rely on
* R_T4 surviving across the tape_run boundary */
Reg look_at;
Reg_(V3_S4) row; /* populate phase: load ux/uy/uz */
union { Reg ux, v_x; } t6; /* populate addr (canonical) → matrix_vector v_x */
@@ -236,17 +227,13 @@ internal MipsAtom* resolve_look_at__pop_mv_trans(AtomArena_R aa,
load_word(r.look_at, R_TapePtr, O_(Binds_ResolveLookAtPopMvTrans,look_at)),
LdSlot_ add_ui_self(R_TapePtr, S_(Binds_ResolveLookAtPopMvTrans)),
/* Load scratch base via immediate (Scratchpad_Loc = 0x1F800000). We can't rely on
* R_T4 (= R_ResolveScratch) surviving across the tape_run boundary — the compiler
* treats it as clobberable per the tape_run asm_clobber list. Baking the scratch
* address via load_word_imm is robust. */
mac_load_word_imm(r.scratch, Scratchpad_Loc),
/* --- Scratch addresses for ux/uy/uz/eye (populate phase; t6/t7/t8 alias ux/uy/uz) --- */
add_si(r.t6.ux, r.scratch, O_(ResolveLookAtScratch, ux)), LdSlot_
add_si(r.t7.uy, r.scratch, O_(ResolveLookAtScratch, uy)),
add_si(r.t8.uz, r.scratch, O_(ResolveLookAtScratch, uz)),
add_si(r.eye, r.scratch, O_(ResolveLookAtScratch, eye)),
/* --- Scratch addresses for ux/uy/uz/eye (populate phase; t6/t7/t8 alias ux/uy/uz).
* R_ScratchBase (= R_SP) holds 0x1F800000; no per-atom bake is required because
* R_SP is a tape carrier preserved across atoms. --- */
add_si(r.t6.ux, R_ScratchBase, O_(ResolveLookAtScratch, ux)), LdSlot_
add_si(r.t7.uy, R_ScratchBase, O_(ResolveLookAtScratch, uy)),
add_si(r.t8.uz, R_ScratchBase, O_(ResolveLookAtScratch, uz)),
add_si(r.eye, R_ScratchBase, O_(ResolveLookAtScratch, eye)),
/* --- POPULATE phase: write look_at->m[][] from ux/uy/uz as packed S2 --- */
mac_load_v3s4(r.row, r.t6.ux, 0), LdSlot_ mac_store_v3s2(r.row, r.look_at, O_(MT3_S2S4, m[0])),