#![allow(
clippy::suboptimal_flops,
clippy::suspicious_operation_groupings,
reason = "Preserve the pinned scalar quantizer's separate binary32 arithmetic."
)]
use super::{Q4_1, Q5_0, Q5_1, Q8_1, Q8Block, finite, half_bits, integer_float, quantized, scale};
use crate::{Result, invalid};
fn half(value: f32) -> Result<[u8; 2]> {
let bits = half_bits(finite(value)?);
finite(bonsai_ternary::half_to_float(bits))?;
Ok(bits.to_le_bytes())
}
fn codes(kind: u32, block: &[u8]) -> [i16; 32] {
let affine = matches!(kind, Q4_1 | Q5_1);
let five = kind != Q4_1;
let offset = if affine { 4 } else { 2 };
let high = if five {
&block[offset..offset + 4]
} else {
&[]
};
let low = &block[offset + if five { 4 } else { 0 }..];
std::array::from_fn(|index| {
let mut value = i16::from((low[index % 16] >> (4 * (index / 16))) & 15);
if five {
value |= i16::from((high[index / 8] >> (index % 8)) & 1) << 4;
}
value - if affine { 0 } else { 16 }
})
}
pub(super) fn decode(kind: u32, block: &[u8], output: &mut Vec<f32>) -> Result<()> {
let d = scale(block)?;
let minimum = if matches!(kind, Q4_1 | Q5_1) {
scale(&block[2..])?
} else {
0.0
};
if kind == Q8_1 {
scale(&block[2..])?;
output.extend(
block[4..]
.iter()
.map(|&byte| f32::from(i8::from_ne_bytes([byte])) * d),
);
} else {
output.extend(codes(kind, block).map(|code| {
let value = f32::from(code) * d;
if kind == Q5_0 { value } else { value + minimum }
}));
}
Ok(())
}
fn pack(kind: u32, d: f32, minimum: f32, values: &[u8; 32], output: &mut Vec<u8>) -> Result<()> {
output.extend(half(d)?);
if matches!(kind, Q4_1 | Q5_1) {
output.extend(half(minimum)?);
}
if kind != Q4_1 {
let mut high = [0_u8; 4];
for (index, value) in values.iter().enumerate() {
high[index / 8] |= ((value >> 4) & 1) << (index % 8);
}
output.extend(high);
}
output.extend((0..16).map(|index| (values[index] & 15) | ((values[index + 16] & 15) << 4)));
Ok(())
}
pub(super) fn encode(kind: u32, input: &[f32], output: &mut Vec<u8>) -> Result<()> {
for values in input.as_chunks::<32>().0 {
if kind == Q8_1 {
let maximum = values
.iter()
.fold(0.0_f32, |maximum, value| maximum.max(value.abs()));
let d = maximum / 127.0;
let inverse = if d == 0.0 { 0.0 } else { finite(1.0 / d)? };
let mut packed = [0_i8; 32];
for (target, &value) in packed.iter_mut().zip(values) {
*target = quantized((value * inverse).round())?;
}
let sum: i32 = packed.iter().map(|&value| i32::from(value)).sum();
output.extend(half(d)?);
output.extend(half(integer_float(sum) * d)?);
output.extend(packed.iter().flat_map(|value| value.to_le_bytes()));
continue;
}
let affine = kind != Q5_0;
let mut minimum = f32::MAX;
let mut maximum = if affine { -f32::MAX } else { 0.0 };
for &value in values {
if value < minimum {
minimum = value;
}
if (affine && value > maximum) || (!affine && value.abs() > maximum.abs()) {
maximum = value;
}
}
let d = if affine {
(maximum - minimum) / if kind == Q4_1 { 15.0 } else { 31.0 }
} else {
maximum / -16.0
};
let inverse = if d == 0.0 { 0.0 } else { finite(1.0 / d)? };
let mut packed = [0; 32];
for (code, &value) in packed.iter_mut().zip(values) {
let shifted = if affine {
(value - minimum) * inverse + 0.5
} else {
value * inverse + 16.5
};
*code = u8::try_from(quantized(shifted.trunc().min(if kind == Q4_1 {
15.0
} else {
31.0
}))?)?;
}
pack(kind, d, minimum, &packed, output)?;
}
Ok(())
}
fn affine(input: &[f32; 32], weights: &[f32; 32], limit: u8) -> Result<(f32, f32, [u8; 32])> {
let mut minimum = input[0];
let mut maximum = input[0];
let mut sum_weight = weights[0];
let mut sum_input = weights[0] * input[0];
for index in 1..32 {
if input[index] < minimum {
minimum = input[index];
}
if input[index] > maximum {
maximum = input[index];
}
sum_weight += weights[index];
sum_input += weights[index] * input[index];
}
if minimum > 0.0 {
minimum = 0.0;
}
if maximum <= minimum {
return Ok((0.0, minimum, [0; 32]));
}
let inverse = finite(f32::from(limit) / (maximum - minimum))?;
let mut d = finite(1.0 / inverse)?;
let assign = |inverse: f32, minimum: f32, values: &mut [u8; 32]| -> Result<()> {
for (code, &value) in values.iter_mut().zip(input) {
*code = u8::try_from(quantized(
(inverse * (value - minimum))
.round_ties_even()
.clamp(0.0, f32::from(limit)),
)?)?;
}
Ok(())
};
let mut best_codes = [0; 32];
assign(inverse, minimum, &mut best_codes)?;
let error = |d: f32, m: f32, values: &[u8; 32]| -> f32 {
let mut sum = 0.0;
for index in 0..32 {
let diff = d * f32::from(values[index]) + m - input[index];
sum += weights[index] * (diff * diff);
}
sum
};
let mut best_error = finite(error(d, minimum, &best_codes))?;
for step in 0_u8..=36 {
let inverse =
finite((-0.9 + 0.05 * f32::from(step) + f32::from(limit)) / (maximum - minimum))?;
let mut candidate = [0; 32];
assign(inverse, minimum, &mut candidate)?;
let mut sum_code = 0.0;
let mut sum_squared = 0.0;
let mut sum_product = 0.0;
for index in 0..32 {
let code = f32::from(candidate[index]);
let weight = weights[index];
sum_code += weight * code;
sum_squared += weight * code * code;
sum_product += weight * code * input[index];
}
let determinant = finite(sum_weight * sum_squared - sum_code * sum_code)?;
if determinant > 0.0 {
let mut candidate_d =
finite((sum_weight * sum_product - sum_input * sum_code) / determinant)?;
let mut candidate_m =
finite((sum_squared * sum_input - sum_code * sum_product) / determinant)?;
if candidate_m > 0.0 {
candidate_m = 0.0;
candidate_d = finite(sum_product / sum_squared)?;
}
let candidate_error = finite(error(candidate_d, candidate_m, &candidate))?;
if candidate_error < best_error {
best_error = candidate_error;
best_codes = candidate;
d = candidate_d;
minimum = candidate_m;
}
}
}
Ok((d, minimum, best_codes))
}
pub(super) fn weighted(kind: u32, input: &[f32], importance: &[f32]) -> Result<Vec<u8>> {
let mut sum_squared = 0.0;
for &value in input {
sum_squared += value * value;
}
let sigma = finite(sum_squared / super::bounded_count_float(u32::try_from(input.len())?))?;
let mut output = Vec::new();
output.try_reserve_exact(input.len() / 32 * super::layout(kind)?.1)?;
for (values, importance) in input
.as_chunks::<32>()
.0
.iter()
.zip(importance.as_chunks::<32>().0)
{
let mut weights = [0.0; 32];
for index in 0..32 {
weights[index] =
finite(importance[index] * (sigma + values[index] * values[index]).sqrt())?;
}
if kind == Q5_0 {
let (bits, values) = super::weighted_symmetric_block(values, &weights, 16)?;
pack(
kind,
bonsai_ternary::half_to_float(bits),
0.0,
&values,
&mut output,
)?;
} else {
let (d, minimum, values) =
affine(values, &weights, if kind == Q4_1 { 15 } else { 31 })?;
pack(kind, d, minimum, &values, &mut output)?;
}
}
Ok(output)
}
pub(super) fn dot(kind: u32, bytes: &[u8], input: &[Q8Block]) -> Result<f32> {
let (_, size) = super::layout(kind)?;
if !matches!(kind, Q4_1 | Q5_0 | Q5_1) {
return Err(invalid("legacy dot format is not supported"));
}
let mut result = 0.0;
for (block, activation) in bytes.chunks_exact(size).zip(input) {
let integer = super::dot_integer(&codes(kind, block), &activation.values);
let mut value = (scale(block)? * activation.scale) * integer;
if kind != Q5_0 {
value += scale(&block[2..])? * finite(activation.sum)?;
}
result += value;
}
finite(result)
}