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78 lines
2 KiB
WebGPU Shading Language
78 lines
2 KiB
WebGPU Shading Language
// Q16_16 fixed-point arithmetic — shared include
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//
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// This file is a shared WGSL include. The build pipeline should prepend
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// this file to any shader that depends on it, e.g.:
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// cat q16_arithmetic.wgsl target_shader.wgsl > combined.wgsl
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//
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// Scale: 2^16 = 65536
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const Q16_SCALE: u32 = 65536u;
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const Q16_ONE: u32 = 0x00010000u;
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const SIGN_BIT: u32 = 0x80000000u;
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const TWO_POW_32: u32 = 0x100000000u;
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// Extract sign bit as i32 (WGSL: u32 -> bool)
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fn is_neg(v: u32) -> bool {
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return (v & SIGN_BIT) != 0u;
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}
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// Convert unsigned Q16_16 to signed integer
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fn q16_to_int(v: u32) -> i32 {
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return bitcast<i32>(v);
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}
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// Convert signed integer to unsigned Q16_16
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fn int_to_q16(v: i32) -> u32 {
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return bitcast<u32>(v);
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}
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// Q16_16 multiplication: (a * b) >> 16
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fn q16_mul(a: u32, b: u32) -> u32 {
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let a_signed = q16_to_int(a);
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let b_signed = q16_to_int(b);
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let product = i64(a_signed) * i64(b_signed);
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let result = i32(product >> 16);
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return bitcast<u32>(result);
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}
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// Q16_16 division: (a << 16) / b
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fn q16_div(a: u32, b: u32) -> u32 {
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let a_signed = q16_to_int(a);
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let b_signed = q16_to_int(b);
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let num = i64(a_signed) << 16;
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let result = i32(num / i64(b_signed));
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return bitcast<u32>(result);
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}
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// Q16_16 negation
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fn q16_neg(a: u32) -> u32 {
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return int_to_q16(-q16_to_int(a));
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}
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// Q16_16 absolute value
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fn q16_abs(a: u32) -> u32 {
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let s = q16_to_int(a);
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return select(a, q16_neg(a), is_neg(a));
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}
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// Q16_16 addition (saturating)
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fn q16_add(a: u32, b: u32) -> u32 {
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let result = q16_to_int(a) + q16_to_int(b);
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return int_to_q16(result);
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}
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// Q16_16 subtraction (saturating)
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fn q16_sub(a: u32, b: u32) -> u32 {
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let result = q16_to_int(a) - q16_to_int(b);
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return int_to_q16(result);
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}
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// Q16_16 maximum
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fn q16_max(a: u32, b: u32) -> u32 {
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return select(b, a, q16_to_int(a) > q16_to_int(b));
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}
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// Q16_16 minimum
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fn q16_min(a: u32, b: u32) -> u32 {
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return select(b, a, q16_to_int(a) < q16_to_int(b));
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}
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