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/*
Copied from https://github.com/turboderp/exllamav2
*/
#ifndef _qdq_4_cuh
#define _qdq_4_cuh
#include "qdq_util.cuh"
namespace vllm {
namespace gptq {
// Permutation:
//
// 77775555 33331111 66664444 22220000
__forceinline__ __device__ void shuffle_4bit_8(uint32_t* q, int stride) {
uint32_t qa = q[0];
uint32_t qb = 0;
#pragma unroll
for (int i = 0; i < 4; i++) {
uint32_t qa0 = qa & 0x0f;
uint32_t qa1 = (qa & 0xf0) >> 4;
qa >>= 8;
qb |= (qa1 << (i * 4 + 16));
qb |= (qa0 << (i * 4));
}
q[0] = qb;
}
__forceinline__ __device__ void dequant_4bit_8(const uint32_t q_0,
half2 (&dq)[4], int stride,
const uint32_t zero) {
const uint32_t c0 = 0x64006400;
const half y16_ = __float2half_rn(1.0f / 16.0f);
const half2 y16 = __halves2half2(y16_, y16_);
const half_uint16 z1_(0xe400 | zero); // half(-1024.0f - zero);
const half z16_ = __hsub(__int2half_rn(-64), __int2half_rn(zero));
const half2 z1 = __half2half2(z1_.as_half);
const half2 z16 = __half2half2(z16_);
uint32_t qa = q_0;
half2_uint32 q0((qa & 0x000f000f) | c0); // half2(q[ 0], q[ 1]) + 1024
half2_uint32 q1((qa & 0x00f000f0) | c0); // half2(q[ 2], q[ 3]) * 16 + 1024
qa >>= 8;
half2_uint32 q2((qa & 0x000f000f) | c0); // half2(q[ 4], q[ 5]) + 1024
half2_uint32 q3((qa & 0x00f000f0) | c0); // half2(q[ 6], q[ 7]) * 16 + 1024
dq[0] = __hadd2(q0.as_half2, z1);
dq[1] = __hfma2(q1.as_half2, y16, z16);
dq[2] = __hadd2(q2.as_half2, z1);
dq[3] = __hfma2(q3.as_half2, y16, z16);
}
__forceinline__ __device__ void dequant_4bit_8_prep_zero_scale(
const uint32_t zero, const half scale, half2 (&z1z16)[2],
half2 (&y1y16)[2]) {
half_uint16 z1(0xe400 | zero); // half(-1024.0f - zero);
half z16 = __hsub(__int2half_rn(-64), __int2half_rn(zero));
half2 scale2 = __half2half2(scale);
z1z16[0] = __hmul2(scale2, __half2half2(z1.as_half));
z1z16[1] = __hmul2(scale2, __half2half2(z16));
const half y1 = __float2half_rn(1.0f);
const half y16 = __float2half_rn(1.0f / 16.0f);
y1y16[0] = __hmul2(scale2, __half2half2(y1));
y1y16[1] = __hmul2(scale2, __half2half2(y16));
}
__forceinline__ __device__ void dequant_4bit_8_prep_zero(const uint32_t zero,
half2 (&z1z16)[2],
half2 (&y1y16)[2]) {
half_uint16 z1(0xe400 | zero); // half(-1024.0f - zero);
half z16 = __hsub(__int2half_rn(-64), __int2half_rn(zero));
z1z16[0] = __half2half2(z1.as_half);
z1z16[1] = __half2half2(z16);
const half y1 = __float2half_rn(1.0f);
const half y16 = __float2half_rn(1.0f / 16.0f);
y1y16[0] = __half2half2(y1);
y1y16[1] = __half2half2(y16);
}
__forceinline__ __device__ void dequant_4bit_8_gptq(const uint32_t q_0,
half2 (&dq)[4],
half2 (&z1z16)[2],
half2 (&y1y16)[2],
int stride, bool scaled) {
const uint32_t c0 = 0x64006400;
uint32_t qa = q_0;
half2_uint32 q0((qa & 0x000f000f) |
c0); // half2( q[0] + 1024, q[1] + 1024 )
half2_uint32 q1((qa & 0x00f000f0) |
c0); // half2( q[2] * 16 + 1024, q[3] * 16 + 1024 )
qa >>= 8;
half2_uint32 q2((qa & 0x000f000f) |
c0); // half2( q[4] + 1024, q[5] + 1024 )
half2_uint32 q3((qa & 0x00f000f0) |
c0); // half2( q[6] * 16 + 1024, q[7] * 16 + 1024 )
if (scaled) {
dq[0] = __hfma2(q0.as_half2, y1y16[0],
z1z16[0]); // half2( q[0] * s - z * s, q[1] * s - z * s)
dq[1] = __hfma2(q1.as_half2, y1y16[1],
z1z16[1]); // half2( q[2] * s - z * s, q[3] * s - z * s)
dq[2] = __hfma2(q2.as_half2, y1y16[0], z1z16[0]);
dq[3] = __hfma2(q3.as_half2, y1y16[1], z1z16[1]);
} else {
dq[0] = __hadd2(q0.as_half2, z1z16[0]); // half2( q[0] - z, q[1] - z )
dq[1] = __hfma2(q1.as_half2, y1y16[1],
z1z16[1]); // half2( q[2] - z, q[3] - z )
dq[2] = __hadd2(q2.as_half2, z1z16[0]); // half2( q[4] - z, q[5] - z )
dq[3] = __hfma2(q3.as_half2, y1y16[1],
z1z16[1]); // half2( q[6] - z, q[7] - z )
}
}
} // namespace gptq
} // namespace vllm
#endif