MTK mobile SoC summary

Sorted roughly by antutu scores

Type	CPUS, GPU	Note
Dimension 1000	A77 A55 G77	7nm
Dimension 1000L	A77 A55 G77	7nm
Dimension 800	A76 A55 G57	7nm
G90T	A76 A55 G76
G90	A76 A55 G76
P95 P90	A75 A55 PowerVR9446
G80 G70 P65	A75 A55 G52
X30	A73 A53 A35 PowerVR 7XTP-MT4	10nm
P70 P60	A73 A73 G72
P series below	A53 with some GPU	Not recommended

use ccache to accelerate compiling time in CMake

CMake > 3.4.0
define

-DCMAKE_CXX_COMPILER_LAUNCHER=ccache

or add below in CMakeLists.txt

set(CMAKE_CXX_COMPILER_LAUNCHER ccache)

https://stackoverflow.com/a/37828605

make sure your ccache is latest to avoid bugs like

https://stackoverflow.com/a/47097937

clang plugin undefined reference

as https://patchwork.freedesktop.org/patch/219763/ suggestes, reorder the library including sequence

diff --git a/src/gallium/targets/opencl/Makefile.am b/src/gallium/targets/opencl/Makefile.am
index de68a93ad5..f0e1de7797 100644
--- a/src/gallium/targets/opencl/Makefile.am
+++ b/src/gallium/targets/opencl/Makefile.am
@@ -23,11 +23,10 @@  lib@OPENCL_LIBNAME@_la_LIBADD = \
  $(LIBELF_LIBS) \
  $(DLOPEN_LIBS) \
  -lclangCodeGen \
- -lclangFrontendTool \
  -lclangFrontend \
+ -lclangFrontendTool \
  -lclangDriver \
  -lclangSerialization \
- -lclangCodeGen \
  -lclangParse \
  -lclangSema \
  -lclangAnalysis \

llvm opt no effect?

in clang 5.0, it added a function call O0-optnone, which make your modification to llvm ir in passes not effective

compile you code with -Xclang -disable-O0-optnone then it will be effective again

prime nummber (C)

prime nummber
給你一個n，輸出第n個質數

// Comment

#include <stdio.h>
#include <stdint.h>

#define n 10000

uint64_t primes[n];

int main(void){

  int primesSize = 2;
  primes[0] = 2;
  primes[1] = 3; // notice n must >= 2
  for(uint64_t j = 4; j < UINTMAX_MAX; ++j){
    if(primesSize >= n)
      break;
    for(int k = 0; k < primesSize; ++k){
      if(j % primes[k] == 0)
        break;
      else if(primes[k]*primes[k] > j){
        primes[primesSize] = j;
        primesSize++;
        break;
      }
    }
  }
  printf("%lu\n", primes[n-1]);


  return 0;
}

也可以使用6n+-1法 簡易版是在第一層for迴圈加入 if(j%2==0||j%3==0)continue;

even odd sort (C)

給你一個n，接下來有n個整數，對他們排序使得
(1) 偶數在奇數前面
(2) 偶數遞減排序、奇數遞增排序
然後輸出這個數列

// Comment
#include <stdio.h>
#include <stdlib.h>

int lessthan(const void * p, const void * q){
  return *(int*)p - *(int*)q;
}

int greaterthan(const void * p, const void * q){
  return *(int*)q - *(int*)p;
}

void eosort(int * arr, int arrSize){
  int *a1 = (int*)malloc(sizeof(int)*arrSize);
  int *a2 = (int*)malloc(sizeof(int)*arrSize);
  int odd_index = 0;
  int even_index = 0;
  int i;
  for(i = 0; i < arrSize; ++i){
    if(arr[i] % 2){
      a1[odd_index++] = arr[i];
    }
    else
      a2[even_index++] = arr[i];
  }
  qsort(a1, odd_index, sizeof(int), lessthan);
  qsort(a2, even_index, sizeof(int), greaterthan);

  for(i = 0; i < even_index; ++i){
    arr[i] = a2[i];
  }
  for(i = 0; i < odd_index; ++i){
    arr[i + even_index] = a1[i];
  }
}


int main(void){
  int arr[] = {0, 9, 2, 7, 4, 5, 6, 3, 8, 1, 10};
  int arrSize = 11;
  eosort(arr, arrSize);
  int i;
  for(i = 0; i < arrSize; ++i){
    printf("%d ", arr[i]);
  }
  putchar('\n');
  return 0;
}

1004. Max Consecutive Ones III (C)

// Comment
int longestOnes(int* A, int ASize, int K) {
    int result = 0;
    int localmax = 0;
    int indexOfZero = 0;
    for(int i = 0; i < ASize; ++i){
        if(A[i] == 0)
            K--;
        localmax++;
        while(K<0){
            if(A[indexOfZero] == 0){
                K++;
            }
            indexOfZero++;
            
            localmax--;
        }
        result = localmax > result ? localmax : result;
        
    }
    return result;
}