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intiial review on: resolve_look_at__input_and_sub_proc

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ed
2026-08-13 19:42:43 -04:00
parent 640dab7e61
commit b699b47b28
7 changed files with 82 additions and 104 deletions
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code/hello_camera/hello_camera.atom.c
+19 -49
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@@ -188,26 +188,17 @@ typedef Struct_(ResolveLookAtScratch) {
*/
typedef Struct_(Binds_ResolveLookAtSub) {
U4 target; /* U4 (C-side P3_S4* — read by atom 0 directly; NOT a scratchpad address) */
U4 eye; /* U4 (C-side P3_S4* — read by atom 0 directly; staged into scratchpad by atom 0) */
U4 up_in; /* U4 (C-side V3_S4* — read by atom 0 directly; staged into scratchpad by atom 0) */
U4 scratchpad;
P3_S4* target; /* U4 (C-side P3_S4* — read by atom 0 directly; NOT a scratchpad address) */
P3_S4* eye; /* U4 (C-side P3_S4* — read by atom 0 directly; staged into scratchpad by atom 0) */
V3_S4* up_in; /* U4 (C-side V3_S4* — read by atom 0 directly; staged into scratchpad by atom 0) */
ResolveLookAtScratch* scratchpad;
};
/* Atom 0 in the bundle: input_and_sub. Stages C-side inputs into the scratchpad and computes fwd = target - eye.
* Inputs (C-side pointers popped from the tape):
* r_target_ptr : P3_S4* (C-side struct; atom 0 reads target.x/y/z directly)
* r_eye_ptr : P3_S4* (C-side struct; staged into scratchpad at +96/+100/+104)
* r_up_in_ptr : V3_S4* (C-side struct; staged into scratchpad at +128/+132/+136)
* r_scratch : R_ResolveScratch (R_T4) — scratch base, read by atoms 1-6
*
* Bind-pop layout:
* Binds_ResolveLookAtSub
* Staging work:
* * Stage eye.x/y/z → scratch (for atom 6's translation column)
* * Stage up_in.x/y/z → scratch (for atom 2's outer-product operand)
* * Compute fwd = target - eye, store fwd.x/y/z → scratch+0/+4/+8 (for atom 1)
*
* GPR codes (assigned by resolve_look_at_init):
* r_target_ptr : R_T0
* r_eye_ptr : R_T1
@@ -219,56 +210,35 @@ typedef Struct_(Binds_ResolveLookAtSub) {
* r_tmp3 : R_T7 (stage eye/up_in + load target.y)
* R_AT : hardcoded (load eye.y / eye.z / target.z)
* R_V0 : hardcoded (load eye.z / target.z)
*
* Pool cost: 8 GPRs + R_T4 (carrier) + R_AT + R_V0 (hardcoded) = 11 GPRs.
*/
internal MipsAtom* resolve_look_at__input_and_sub_proc(AtomArena_R aa, U4 r_scratch
internal MipsAtom* resolve_look_at__input_and_sub_proc(AtomArena_R aa,
// TODO(Ed): We can resolve scratch at anytime its fixed to a specific address.
U4 r_scratch
, U4 r_target_ptr,U4 r_eye_ptr, U4 r_up_in_ptr
, U4 r_tmp0, U4 r_tmp1, U4 r_tmp2, U4 r_tmp3
) MipsAtom_Proc_(resolve_look_at__input_and_sub, aa, {
/* Pop the 3 C-side pointers + scratch_base from the tape. */
load_word(r_target_ptr, R_TapePtr, O_(Binds_ResolveLookAtSub,target)),
load_word(r_eye_ptr, R_TapePtr, O_(Binds_ResolveLookAtSub,eye)),
load_word(r_up_in_ptr, R_TapePtr, O_(Binds_ResolveLookAtSub,up_in)),
load_word(r_scratch, R_TapePtr, O_(Binds_ResolveLookAtSub,scratchpad)),
add_ui_self( R_TapePtr, S_(Binds_ResolveLookAtSub)),
/* Stage eye.x/y/z into the scratchpad (atom 6 reads these for the translation
* column). Reuse r_tmp0/r_tmp1/r_tmp2. Offsets via O_(ResolveLookAtScratch,*). */
load_word(r_tmp0, r_eye_ptr, O_(P3_S4,x)),
load_word(r_tmp1, r_eye_ptr, O_(P3_S4,y)),
load_word(r_tmp2, r_eye_ptr, O_(P3_S4,z)),
nop, /* load-delay */
store_word(r_tmp0, r_scratch, O_(ResolveLookAtScratch,eye.x)),
store_word(r_tmp1, r_scratch, O_(ResolveLookAtScratch,eye.y)),
store_word(r_tmp2, r_scratch, O_(ResolveLookAtScratch,eye.z)),
// Stage eye.x/y/z into the scratchpad (atom 6 reads these for the translation column).
mac_load_p3s4( r_tmp0, r_tmp1, r_tmp2, r_eye_ptr, 0),
mac_store_p3s4(r_tmp0, r_tmp1, r_tmp2, r_scratch, O_(ResolveLookAtScratch,eye)),
/* Stage up_in.x/y/z into the scratchpad (atom 2 reads these for the outer
* product with uz). Reuse r_tmp0/r_tmp1/r_tmp2. */
load_word(r_tmp0, r_up_in_ptr, O_(V3_S4,x)),
load_word(r_tmp1, r_up_in_ptr, O_(V3_S4,y)),
load_word(r_tmp2, r_up_in_ptr, O_(V3_S4,z)),
nop, /* load-delay */
store_word(r_tmp0, r_scratch, O_(ResolveLookAtScratch,up_in.x)),
store_word(r_tmp1, r_scratch, O_(ResolveLookAtScratch,up_in.y)),
store_word(r_tmp2, r_scratch, O_(ResolveLookAtScratch,up_in.z)),
/* Stage up_in.x/y/z into the scratchpad. */
mac_load_p3s4( r_tmp0, r_tmp1, r_tmp2, r_up_in_ptr, 0),
mac_store_p3s4(r_tmp0, r_tmp1, r_tmp2, r_scratch, O_(ResolveLookAtScratch,up_in)),
/* Compute fwd = target - eye. */
load_word(r_tmp0, r_target_ptr, O_(P3_S4,x)),
load_word(r_tmp1, r_target_ptr, O_(P3_S4,y)),
load_word(r_tmp2, r_target_ptr, O_(P3_S4,z)),
load_word(r_tmp3, r_eye_ptr, O_(P3_S4,x)),
load_word(R_AT, r_eye_ptr, O_(P3_S4,y)),
load_word(R_V0, r_eye_ptr, O_(P3_S4,z)),
nop, /* load-delay */
sub_u(r_tmp0, r_tmp0, r_tmp3),
sub_u(r_tmp1, r_tmp1, R_AT),
sub_u(r_tmp2, r_tmp2, R_V0),
/* Store fwd.x/y/z (atom 1 reads these as the normalize src). */
store_word(r_tmp0, r_scratch, O_(ResolveLookAtScratch,fwd.x)),
store_word(r_tmp1, r_scratch, O_(ResolveLookAtScratch,fwd.y)),
store_word(r_tmp2, r_scratch, O_(ResolveLookAtScratch,fwd.z)),
mac_load_p3s4(r_tmp0, r_tmp1, r_tmp2, r_target_ptr, 0),
mac_load_p3s4(r_tmp3, R_AT, R_V0, r_eye_ptr, 0),
mac_sub_v3s4(
r_tmp0, r_tmp1, r_tmp2,
r_tmp3, R_AT, R_V0),
mac_store_v3s4(r_tmp0, r_tmp1, r_tmp2, r_scratch, O_(ResolveLookAtScratch,fwd)),
mac_yield()
})