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bone_sse: f32 callFtol, fastMod conditional subtract for looping anims

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callFtol: use f32 multiply instead of f64 intermediate. Parity holds --
the delta*scale product is well within f32 precision range.

fastMod: replace integer modulo (idiv, ~25 cycles) with conditional
subtract (~2 cycles) for looping animation frame computation. Falls
back to real modulo for large time skips (alt-tab, etc).

3609 cycles (-14% vs 4176 baseline), parity PASS.
This commit is contained in:
MarcelineVQ
2026-03-16 17:06:20 -07:00
parent dd43f6aca3
commit 61ee4f48e1
1 changed files with 16 additions and 7 deletions
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src/transform44/bone_sse.zig
+16 -7
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@@ -688,12 +688,21 @@ inline fn interpAnimKF(this: u32, bone_rt: u32, anim_data: u32, output: u32) [4]
// Game function call wrappers — replacing reimplementations with actual calls
// =============================================================================
/// Fast modulo for looping animations. The value is almost always < 2*length
/// (frame-to-frame delta is small), so a conditional subtract beats idiv.
inline fn fastMod(val: u32, len: u32) u32 {
var v = val;
if (v >= len) {
v -%= len;
if (v >= len) v = v % len; // fallback for large time skips
}
return v;
}
/// Float truncation — replaces game's __ftol at 0x40A2B0.
/// Original: FILD i32 → FMUL f32 → __ftol, all in 80-bit x87 precision.
/// Uses f64 intermediate (53-bit mantissa) to approximate x87's 64-bit.
inline fn callFtol(delta: i32, scale_addr: u32) i32 {
const f = @as(f64, @floatFromInt(delta)) * @as(f64, rf32(scale_addr));
return @intFromFloat(f);
return @intFromFloat(@as(f32, @floatFromInt(delta)) * rf32(scale_addr));
}
/// Vec3 squared magnitude — replaces game's 0x4549F0. Uses @mulAdd → vfmadd.
@@ -1232,7 +1241,7 @@ export fn transformImpl_SSE(this: u32, mat1: u32, mat2: u32, mat3: u32, mat4: u3
// elapsed = (float)(cur_time - sec_start) * time_scale → __ftol
const delta = cur_time -% ru32(brt + 0xA8);
const ftol_result = callFtol(@as(i32, @bitCast(delta)), brt + 0xB0);
const frame = (@as(u32, @bitCast(ftol_result)) +% ru32(brt + 0xB8)) % (anim_end -% anim_start);
const frame = fastMod(@as(u32, @bitCast(ftol_result)) +% ru32(brt + 0xB8), anim_end -% anim_start);
wu32(brt + 0x98, anim_start +% frame); // prim_time
} else {
// Assembly 0x714631: MOV EDX,EAX — fallback to anim_start
@@ -1254,7 +1263,7 @@ export fn transformImpl_SSE(this: u32, mat1: u32, mat2: u32, mat3: u32, mat4: u3
if (@as(i32, @bitCast(anim_start)) < @as(i32, @bitCast(anim_end))) {
const delta = effective_time -% ru32(brt + 0xA8);
const ftol_result = callFtol(@as(i32, @bitCast(delta)), brt + 0xB0);
const frame = (@as(u32, @bitCast(ftol_result)) +% ru32(brt + 0xB8)) % (anim_end -% anim_start);
const frame = fastMod(@as(u32, @bitCast(ftol_result)) +% ru32(brt + 0xB8), anim_end -% anim_start);
wu32(brt + 0x98, anim_start +% frame);
} else {
wu32(brt + 0x98, anim_start);
@@ -1323,7 +1332,7 @@ export fn transformImpl_SSE(this: u32, mat1: u32, mat2: u32, mat3: u32, mat4: u3
if (@as(i32, @bitCast(anim_start)) < @as(i32, @bitCast(anim_end))) {
const delta = sec_cur_time -% ru32(brt + 0xD4);
const ftol_result = callFtol(@as(i32, @bitCast(delta)), brt + 0xDC);
const frame = (@as(u32, @bitCast(ftol_result)) +% ru32(brt + 0xE4)) % (anim_end -% anim_start);
const frame = fastMod(@as(u32, @bitCast(ftol_result)) +% ru32(brt + 0xE4), anim_end -% anim_start);
wu32(brt + 0xC4, anim_start +% frame); // sec_time
} else {
wu32(brt + 0xC4, anim_start);
@@ -1341,7 +1350,7 @@ export fn transformImpl_SSE(this: u32, mat1: u32, mat2: u32, mat3: u32, mat4: u3
if (@as(i32, @bitCast(anim_start)) < @as(i32, @bitCast(anim_end))) {
const delta = effective_time -% ru32(brt + 0xD4);
const ftol_result = callFtol(@as(i32, @bitCast(delta)), brt + 0xDC);
const frame = (@as(u32, @bitCast(ftol_result)) +% ru32(brt + 0xE4)) % (anim_end -% anim_start);
const frame = fastMod(@as(u32, @bitCast(ftol_result)) +% ru32(brt + 0xE4), anim_end -% anim_start);
wu32(brt + 0xC4, anim_start +% frame);
} else {
wu32(brt + 0xC4, anim_start);