pkhuong

(defun multiplicative-inverse (x bitwidth)
  "Iteratively finds the multiplicative inverse of x mod 2^bitwidth.

   The induction step uses the fact that, for a given inverse x^-1
   with (x * x^-1) mod 2^w == 1, (x * x^-1) mod 2^{w - 1} == 1 as
   well.  We start with the trivial inverse mod 2, and increase the
   bitwidth iteratively: given inv_{w - 1} = x^-1 mod 2^{w - 1},
   x^-1 mod 2^w is either inv_{w - 1}, or inv_{w - 1} + 2^{w - 1}."
  (assert (oddp x))
  (let ((inverse 1))

pkhuong

#include "trait.h"

static inline int
cmp_int(int x, int y)
{
        if (x == y)
                return 0;
        return x < y ? -1 : 1;
}

pkhuong

Keybase proof

I hereby claim:

• I am pkhuong on github.
• I am pkhuong (https://keybase.io/pkhuong) on keybase.
• I have a public key ASCqsTjZLilMzRmz9kuPxAn3nF3Z-gOZMEtG8-G3qi4o8go

To claim this, I am signing this object:

pkhuong

import math
import struct
import unittest
import hypothesis.strategies as st
from hypothesis.stateful import Bundle, RuleBasedStateMachine, consumes, invariant, multiple, precondition, rule


class VarianceStack:
    def __init__(self):
        self.n = 0

pkhuong

#define RUN_ME /*
exec cc -O2 -W -Wall -std=c99 -shared $0 -o "$(basename $0 .c).so" -fPIC
*/

/*
 * Copyright 2019 Paul Khuong
 * SPDX-License-Identifier:  BSD-2-Clause
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions

pkhuong

FROM alpine:latest AS builder
RUN echo "foo" > /foo.txt

FROM scratch
COPY --from=builder /*.txt .

pkhuong

(defstruct div-by-mul-constants
  ;; Implement truncated integer by `divisor` with a fixed point
  ;; approximation.
  (divisor 0 :type sb-ext:word
           :read-only t)
  ;; The reciprocal is roughly multipler / 2^(W + shift),
  ;; where W is the word width.
  (multiplier 0 :type sb-ext:word
              :read-only t)
  (shift 0 :type sb-ext:word

pkhuong

diff --git a/src/compiler/x86-64/simd-pack-256.lisp b/src/compiler/x86-64/simd-pack-256.lisp
index e6bdc560c..228f2018a 100644
--- a/src/compiler/x86-64/simd-pack-256.lisp
+++ b/src/compiler/x86-64/simd-pack-256.lisp
@@ -189,7 +189,7 @@
   (:policy :fast-safe)
   (:generator 3
     (inst vextracti128 tmp x 1)
-    (inst vpextrq dst x 1)))
+    (inst vpextrq dst tmp 1)))

pkhuong

;; load https://github.com/pkhuong/csm

(defun player-one ()
  (* (random 1d0) (random 1d0)))

(defun player-two ()
  (expt (random 1d0) 2))

(defun player-one-wins ()
  (> (player-one) (player-two)))

pkhuong

(sb-c:defknown prefetch ((member :nta :t0 :t1 :t2)
                         sb-sys:system-area-pointer sb-vm:signed-word
                         (member 2 4 8 16)
                         fixnum)
    (values &optional)
    (sb-c:any sb-c:always-translatable) :overwrite-fndb-silently t)

(sb-c:define-vop (prefetch)
  (:translate prefetch)
  (:policy :fast-safe)