Fabian 'ryg' Giesen rygorous
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| Avoid, avoid, | |
| Avoid pop culture | |
| avoid! | |
| Avoid, | |
| avoid pop culture | |
| then you'll feel better | |
| Ahhhhhhhh! | |
| Avoid, avoid |
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| #include <stdint.h> | |
| typedef unsigned char U8; | |
| typedef unsigned short U16; | |
| typedef unsigned int U32; | |
| typedef unsigned long long U64; | |
| typedef intptr_t SINTa; | |
| struct KernelState | |
| { |
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| import random | |
| # Determinant predicate (line sidedness test) | |
| def det3x3_pt(p, q, r): | |
| a = (q[0] - p[0], q[1] - p[1]) | |
| b = (r[0] - p[0], r[1] - p[1]) | |
| return a[0]*b[1] - a[1]*b[0] | |
| def convex_hull(points): | |
| # sorts points by x then y which works for us (we only need the sort by x part here, but it doesn't hurt) |
rygorous
/ gist:e6076b706ad1f423f4fbc79227b72fb2
Last active
May 25, 2020 05:15
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| ---- On Ryzen 3950X | |
| SimpleProf :seconds calls count : clk/call clk/count | |
| search_one : 0.3081 1 8388480 : 1078358365.0 128.55 | |
| search_one_pf : 0.3415 1 8388480 : 1195232920.0 142.49 <-- speculative prefetching (next options for L and R) | |
| search_multi2 : 0.3062 1 8388480 : 1071663705.0 127.75 | |
| search_multi4 : 0.2454 1 8388480 : 859008465.0 102.40 | |
| search_multi8 : 0.2113 1 8388480 : 739533515.0 88.16 | |
| search_multi16 : 0.1996 1 8388480 : 698443550.0 83.26 | |
| search_multi32 : 0.1785 1 8388480 : 624785840.0 74.48 |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>Some fun HTML5 stuff</title> | |
| <body> | |
| <p>All of this is valid syntax! | |
| <ul> | |
| <li>Don't need to close paragraphs (that one's old) | |
| <li>or list items | |
| <li>since it's clear from context! |
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| // ---- triangle rasterizer | |
| #define SUBPIXEL_SHIFT 8 | |
| #define SUBPIXEL_SCALE (1 << SUBPIXEL_SHIFT) | |
| static RADINLINE S64 det2x2(S32 a, S32 b, S32 c, S32 d) | |
| { | |
| S64 r = (S64) a*d - (S64) b*c; | |
| return r >> SUBPIXEL_SHIFT; | |
| } |
rygorous
/ gist:a549832e23b913ac70237d23c1600f8a
Created
August 16, 2019 22:37
pseudo-ucode expansion for LOOP <dest>
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| lea rcx, [rcx-1] ; decrement rcx w/o flag update | |
| mov temp0, rax ; save rax that we're about to trash | |
| lahf ; save original flags | |
| test rcx, rcx ; check whether updated rcx is zero | |
| setz temp1 ; temp1 = 1 if rcx=0, 0 otherwise | |
| sahf ; restore flags | |
| mov rax, temp0 ; restore rax | |
| jecxz temp1, dest ; jump if temp1 is zero, not rcx (doesn't exist in regular ISA but rcx is renamed anyway so the internal uop can do any source) | |
| NOTE the actual ucode expansion probably doesn't have the MOVs since I would expect the internal LAHF/SAHF uops |
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| @echo off | |
| setlocal | |
| cd %~dp0 | |
| call vcvars amd64 | |
| ..\..\bin\win32\nasm -f win64 -g -o histo_asm.obj histo_asm.nas || exit /b 1 | |
| cl /Zi /O2 /nologo histotest.cpp histo_asm.obj || exit /b 1 |
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| #include <stdint.h> | |
| #include <stdio.h> | |
| #include <string.h> | |
| #include <emmintrin.h> | |
| static uint32_t recip(uint32_t bits) | |
| { | |
| uint32_t u; | |
| float f; | |
| memcpy(&f, &bits, sizeof(bits)); |
rygorous
/ convergents.py
Created
June 6, 2019 23:14
Approximate rational fractions using convergents of the continued fraction expansion
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| # Returns (exact, p, q) where p/q is an approximation to numer/denom and exact is true if | |
| # the approximation is exact. | |
| def convergent(numer, denom, limit): | |
| """Find an approximation to numer/denom with neither numerator nor denominator above limit""" | |
| prev_p, cur_p = 0, 1 | |
| prev_q, cur_q = 1, 0 | |
| rest_p = numer | |
| rest_q = denom | |
| while rest_q != 0: |