记忆逆转游戏

本文介绍了记忆逆转游戏的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！ 前几天我被某人发布了关于 " mirror-imaging"的方法的好奇心。一个字节中的位。我认为可能有趣的是 编写一个完全可移植的算法，用于镜像（即反转）一整块内存，并使算法尽可能快可能（是的， 我意识到它在某些机器上可能比在其他机器上更快，但仍然，一个 可以瞄准全面的高平均效率。） 无论如何，这是我的最新代码，随意篡改。我没有经过用细齿梳梳理它的b $ b，所以它可能包含一两个bug。它用于反转一个字节中的位的方法是基于看起来像 的代码： | （（unsigned）val& 128）> 7 | （（unsigned）val& 64）> 6 这是： #include< assert.h> #include< stddef.h> #include< limits.h> #include< stdio.h> / *以下宏设置指定的 唯一位索引。 （使用IMAX_BITS来执行断言会更好 而不是sizeof（无符号）* CHAR_BIT）。 * / #define ISOLATE_BIT（索引）（\ 断言（（索引）< sizeof（unsigned）* CHAR_BIT），\ 1U<<（index）） / *下一个宏给出了反转位索引， 例如对于8位字节： 0 - 7 4 - 3 1 - 6 5 - 2 2 - 5 6 - 1 3 - 4 7 - 0 * / #define REVERSAL_BIT_POSITION（index）（\ 断言（（索引）< CHAR_BIT），\ CHAR_BIT-1 - （索引）） char unsigned ByteReversal（char unsigned val） { 无符号索引，反转= 0; / *先处理向左移动。 * / for（index = 0; index！= CHAR_BIT / 2; ++ index） { reversal | =（（unsigned）val& ISOLATE_BIT（index）） << REVERSAL_BIT_POSITION（index） - index; } / *现在处理向右移动。 * / for（; index！= CHAR_BIT; ++ index） { reversal | =（（unsigned） val& ISOLATE_BIT（index）） } 退货逆转; } void ReverseMemory（void * const pv，size_t const quantity_bytes） { int const assert_dummy =（assert（!! pv），0） ; char unsigned * p = pv， * q = p +（quantity_bytes - 1）; for（; qp; ++ p， - q） { unsigned const temp = ByteReversal（* p）; * p = ByteReversal（* q）; * q = temp; } } int main（void） { unsigned arr [64] = {0,1,2,3,4,5,6,7,8,9， 10,11,12,13,14,15,16,17,18,19， 20,21,22,23,24,25,26， 27,28,29， 30,31,32,33,34,35,36,37,38,39， 40,41,42,43， 44,45,46,47,48,49， 50,51,52,53,54,55,56,57,58,59， 60， 61,62,63}; unsigned const * p，* const q = arr + sizeof arr / sizeof * arr; p = arr; do printf（"％u"，* p ++）; while（p！= q）; puts（""）; ReverseMemory（arr，sizeof arr）; p = arr; do printf（"％u"，* p ++）; while（p！= q）; put（""）; ReverseMemory（arr，sizeof arr）; p = arr; do printf（"％u，* p ++）; while（p！= q）; puts（""）; } - Frederick Gotham 解决方案 } 退货逆转; } void ReverseMemory（void * const pv，size_t const quantity_bytes） { int const assert_dummy =（assert（!! pv），0） ; char unsigned * p = pv， * q = p +（quantity_bytes - 1）; for（; qp; ++ p， - q） { unsigned const temp = ByteReversal（* p）; * p = ByteReversal（* q）; * q = temp; } } int main（void） { unsigned arr [64] = {0,1,2,3,4,5,6,7,8,9， 10,11,12,13,14,15,16,17,18,19， 20,21,22,23,24,25,26， 27,28,29， 30,31,32,33,34,35,36,37,38,39， 40,41,42,43， 44,45,46,47,48,49， 50,51,52,53,54,55,56,57,58,5 9， 60,61,62,63}; 无符号const * p，* const q = arr + sizeof arr / sizeof * arr; p = arr; do printf（"％u"，* p ++）; while（p！= q ）; puts（""）; ReverseMemory（arr，sizeof arr）; p = arr; do printf（"％u"，* p ++）; while（p！= q）; puts（"" ;）; ReverseMemory（arr，sizeof arr）; p = arr; do printf（"％u" ;，* p ++）; while（p！= q）; puts（""）; } - Frederick Gotham 你的ReverseMemory函数有一个小BUG。 当quantity_bytes时，它无法正常工作。参数是一个奇怪的 数。 这是我的代码，请指出错误： #include< assert.h> #include< stddef.h> #include< limits.h> #include< stdio.h> #include< stdlib.h> #include< memory.h> //定义字节类型这台机器 typedef unsigned char Tchar; //反向函数的函数指针 typedef Tchar（* ptrRevCharFun） （Tchar）; //定义反向函数 Tchar RevChar8（Tchar）; //仅适用于8位字符 // Tchar RevChar16（Tchar）; //如果你需要 // Tchar RevChar32（Tchar）; //如果你需要 ///////////////////////////////////// ////////// //通过本机的CHAR_BIT选择正确的功能 //如果你没有为这个 //机器定义一个函数，你将得到一个编译时错误 #if CHAR_BIT == 8 ptrRevCharFun g_pFunRevChar = RevChar8; #endif #if CHAR_BIT == 16 ptrRevCharFun g_pFunRevChar = RevChar16; //如果你需要 #endif #if CHAR_BIT == 32 ptrRevCharFun g_pFunRevChar = RevChar32; //如果你需要 #endif /////////////////////////// //////////////////// //仅限8位字符的反向函数 Tchar RevChar8（Tchar值） { value =（（值& 0x0fu）<< 4）| （（值& 0xf0u）> 4）; value =（（值& 0x33u）<< 2）| （（值& 0xccu）> 2）; return（（值& 0x55u）<< 1）| （（值& 0xaau）> 1）; } //内存反转 void RevMemory（Tchar *开始， Tchar *结束） { Tchar temp; for（end--; begin < = end; ++ begin， - end） { temp = g_pFunRevChar（* begin）; //如果你在这里找到了未找到标识符 错误， * begin = g_pFunRevChar（* end）; //也许你需要定义一个新的 反转函数 * end = temp; //这个新机器。 } } //用于调试和测试 void ShowBinChar（Tchar值， Tchar op =''''） { Tchar mask = 1u<< （CHAR_BIT - 1）; int i; for（i = 0; i< CHAR_BIT; ++ i） { if（value& mask）putchar（''1''）; else putchar（''0''）; value<< = 1; } putchar（op）; } //用于调试和测试 void ShowBinMemory（Tchar * begin， Tchar *结束， Tchar op =''\ n''） { while（begin！= end） ShowBinChar（*开始++）; putchar（op）; } int main（） { Tchar a [] = {''a''，''b''，''c''，'d''，''e''} ; ShowBinMemory（a，a + sizeof（a））; RevMemory（a，a + sizeof（a））; ShowBinMemory（a，a + sizeof（a））; } } 退货逆转; } void ReverseMemory（void * const pv，size_t const quantity_bytes） { int const assert_dummy =（assert（!! pv），0） ; char unsigned * p = pv， * q = p +（quantity_bytes - 1）; for（; qp; ++ p， - q） { unsigned const temp = ByteReversal（* p）; * p = ByteReversal（* q）; * q = temp; } } int main（void） { unsigned arr [64] = {0,1,2,3,4,5,6,7,8,9， 10,11,12,13,14,15,16,17,18,19， 20,21,22,23,24,25,26， 27,28,29， 30,31,32,33,34,35,36,37,38,39， 40,41,42,43， 44,45,46,47,48,49， 50,51,52,53,54,55,56,57,58,5 9， 60,61,62,63}; 无符号const * p，* const q = arr + sizeof arr / sizeof * arr; p = arr; do printf（"％u"，* p ++）; while（p！= q ）; puts（""）; ReverseMemory（arr，sizeof arr）; p = arr; do printf（"％u"，* p ++）; while（p！= q）; puts（"" ;）; ReverseMemory（arr，sizeof arr）; p = arr; do printf（"％u" ;，* p ++）; while（p！= q）; puts（""）; } - Frederick Gotham 你的ReverseMemory函数有一个小BUG。 当quantity_bytes时，它无法正常工作。参数是一个奇怪的 数。 这是我的代码，请指出错误： #include< assert.h> #include< stddef.h> #include< limits.h> #include< stdio.h> #include< stdlib.h> #include< memory.h> //定义字节类型这台机器 typedef unsigned char Tchar; //反向函数的函数指针 typedef Tchar（* ptrRevCharFun） （Tchar）; //定义反向函数 Tchar RevChar8（Tchar）; //仅适用于8位字符 // Tchar RevChar16（Tchar）; //如果你需要 // Tchar RevChar32（Tchar）; //如果你需要 ///////////////////////////////////// ////////// //通过本机的CHAR_BIT选择正确的功能 //如果你没有为这个 //机器定义一个函数，你将得到一个编译时错误 #if CHAR_BIT == 8 ptrRevCharFun g_pFunRevChar = RevChar8; #endif #if CHAR_BIT == 16 ptrRevCharFun g_pFunRevChar = RevChar16; //如果你需要 #endif #if CHAR_BIT == 32 ptrRevCharFun g_pFunRevChar = RevChar32; //如果你需要 #endif /////////////////////////// //////////////////// //仅限8位字符的反向函数 Tchar RevChar8（Tchar值） { value =（（值& 0x0fu）<< 4）| （（值& 0xf0u）> 4）; value =（（值& 0x33u）<< 2）| （（值& 0xccu）> 2）; return（（值& 0x55u）<< 1）| （（值& 0xaau）> 1）; } //内存反转 void RevMemory（Tchar *开始， Tchar *结束） { Tchar temp; for（end--; begin < = end; ++ begin， - end） { temp = g_pFunRevChar（* begin）; * begin = g_pFunRevChar （*结束）; * end = temp; } } //用于调试和测试 void ShowBinChar（Tchar值， Tchar op =''''） { Tchar mask = 1u<< （CHAR_BIT - 1）; int i; for（i = 0; i< CHAR_BIT; ++ i） { if（value& mask）putchar（''1''）; else putchar（''0''）; value<< = 1; } putchar（op）; } //用于调试和测试 void ShowBinMemory（Tchar * begin， Tchar *结束， Tchar op =''\ n''） { while（begin！= end） ShowBinChar（*开始++）; putchar（op）; } int main（） { Tchar a [] = {''a''，''b''，''c''，'d''，''e''} ; ShowBinMemory（a，a + sizeof（a））; RevMemory（a，a + sizeof（a））; ShowBinMemory（a，a + sizeof（a））; } 请不要使用全部大写 - 这不是英语通常写的 。 Simpy写表或bug，而不是TABLE或BUG。 我有机会查看代码。 _every_ machine上的字节类型是unsigned char。 你忘记了： 9-bit char'' s 21-bit char'的32位字符' 11-bit char'的22-bit char'的33位字符' 12-bit char'的23-bit char'的34位字符' 13-bit char'的24-bit char'的35-bit char' 's 14-bit char'的25-bit char'的36-bit char'' 15-bit char'的26-bit char '的37位字符' 16位字符'的27位字符'的38位字符' 17位char'的28-bit char'的39-bit char'' 18-bit char'的29-bit char'的40-bit char''s&br / > 19-bit char'的30-bit char'的41位字符' 20-bit char'的31-bit char'的42- Bit char's 所有代码都发布到comp.lang.c sh应该是完全可移植的，我的意思是 应该在任何conformaning实现上编译和运行正确。您发布的 代码__完全便携。 - Frederick GothamI was intrigued by someone the other day who posted regarding methods of"mirror-imaging" the bits in a byte. I thought it might be interesting towrite a fully-portable algorithm for mirror-imaging (i.e. reversing) anentire chunk of memory, and making the algorithm as fast as possible (yes,I realise it may be faster on some machines than on others, but still, onecan aim for pretty high average efficiency across the board.)Anyway, here''s my latest code, feel free to tamper. I haven''t gone throughit with a fine-tooth comb, so it might contain a bug or two. The method ituses for reversing bits in a byte is based on the code that lookedsomething like:| ((unsigned)val & 128) >7| ((unsigned)val & 64) >6Here it is:#include <assert.h>#include <stddef.h>#include <limits.h>#include <stdio.h>/* The following macro sets a specifiedsole bit index. (It would be betterto perform the assertion using IMAX_BITSrather than sizeof(unsigned)*CHAR_BIT).*/#define ISOLATE_BIT(index) (\assert((index) < sizeof(unsigned)*CHAR_BIT), \1U << (index) )/* The next macro gives us the reversed bit index,e.g. for 8-Bit bytes:0 - 7 4 - 31 - 6 5 - 22 - 5 6 - 13 - 4 7 - 0*/#define REVERSAL_BIT_POSITION(index) (\assert((index) < CHAR_BIT), \CHAR_BIT-1 - (index) )char unsigned ByteReversal(char unsigned val){unsigned index, reversal = 0;/* Deal with shifting to the left first. */for(index = 0; index != CHAR_BIT/2; ++index){reversal |= ((unsigned)val & ISOLATE_BIT(index))<< REVERSAL_BIT_POSITION(index) - index;}/* Now deal with shifting to the right. */for(; index != CHAR_BIT; ++index){reversal |= ((unsigned)val & ISOLATE_BIT(index))}return reversal;}void ReverseMemory(void *const pv,size_t const quantity_bytes){int const assert_dummy = (assert(!!pv),0);char unsigned *p = pv,*q = p + (quantity_bytes - 1);for( ; q p; ++p, --q){unsigned const temp = ByteReversal(*p);*p = ByteReversal(*q);*q = temp;}}int main(void){unsigned arr[64] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63};unsigned const *p, *const q = arr + sizeof arr/sizeof*arr;p = arr;do printf("%u ",*p++);while (p!=q);puts("");ReverseMemory(arr,sizeof arr);p = arr;do printf("%u ",*p++);while (p!=q);puts("");ReverseMemory(arr,sizeof arr);p = arr;do printf("%u ",*p++);while (p!=q);puts("");}--Frederick Gotham 解决方案 } return reversal;}void ReverseMemory(void *const pv,size_t const quantity_bytes){ int const assert_dummy = (assert(!!pv),0); char unsigned *p = pv, *q = p + (quantity_bytes - 1); for( ; q p; ++p, --q) { unsigned const temp = ByteReversal(*p); *p = ByteReversal(*q); *q = temp; }}int main(void){ unsigned arr[64] = {0,1,2,3,4,5,6,7,8,9, 10,11,12,13,14,15,16,17,18,19, 20,21,22,23,24,25,26,27,28,29, 30,31,32,33,34,35,36,37,38,39, 40,41,42,43,44,45,46,47,48,49, 50,51,52,53,54,55,56,57,58,59, 60,61,62,63}; unsigned const *p, *const q = arr + sizeof arr/sizeof*arr; p = arr; do printf("%u ",*p++); while (p!=q); puts(""); ReverseMemory(arr,sizeof arr); p = arr; do printf("%u ",*p++); while (p!=q); puts(""); ReverseMemory(arr,sizeof arr); p = arr; do printf("%u ",*p++); while (p!=q); puts("");}--Frederick GothamYour "ReverseMemory" function has a small BUG.It cannot work rightly while the "quantity_bytes" parameter is a oddnumber.Here''s my code, point out mistakes please:#include <assert.h>#include <stddef.h>#include <limits.h>#include <stdio.h>#include <stdlib.h>#include <memory.h>// Define the Type of Byte of this Machinetypedef unsigned char Tchar;// Function-pointer for Reverse-functionstypedef Tchar (*ptrRevCharFun)(Tchar);// Define Reverse-functionsTchar RevChar8 (Tchar);// for 8-bit char only//Tchar RevChar16 (Tchar);// if you need//Tchar RevChar32 (Tchar);// if you need///////////////////////////////////////////////// To select a correct function by CHAR_BIT of this machine// If you didn''t define a function for this// machine, you will get a compile-time error#if CHAR_BIT == 8ptrRevCharFun g_pFunRevChar = RevChar8;#endif#if CHAR_BIT == 16ptrRevCharFun g_pFunRevChar = RevChar16;// if you need#endif#if CHAR_BIT == 32ptrRevCharFun g_pFunRevChar = RevChar32;// if you need#endif///////////////////////////////////////////////// Reverse-function for 8-bit char onlyTchar RevChar8 (Tchar value){value = ((value & 0x0fu) << 4) | ((value & 0xf0u) >4);value = ((value & 0x33u) << 2) | ((value & 0xccu) >2);return ((value & 0x55u) << 1) | ((value & 0xaau) >1);}// Memory-Reversevoid RevMemory (Tchar *begin,Tchar *end){Tchar temp;for (end--; begin <= end; ++begin, --end){temp = g_pFunRevChar(*begin);// If you got a "identifier not found"error here,*begin = g_pFunRevChar(*end);// Maybe you need to define a newReverse-function*end = temp;// for this new machine.}}// For Debug and Testvoid ShowBinChar (Tchar value,Tchar op = '' ''){Tchar mask = 1u << (CHAR_BIT - 1);int i;for (i = 0; i < CHAR_BIT; ++i){if (value & mask) putchar(''1''); else putchar(''0'');value <<= 1;}putchar(op);}// For Debug and Testvoid ShowBinMemory (Tchar *begin,Tchar *end,Tchar op = ''\n''){while (begin != end)ShowBinChar (*begin++);putchar(op);}int main(){Tchar a[] = {''a'', ''b'', ''c'', ''d'', ''e''};ShowBinMemory (a, a + sizeof(a));RevMemory (a, a + sizeof(a));ShowBinMemory (a, a + sizeof(a));} } return reversal;}void ReverseMemory(void *const pv,size_t const quantity_bytes){ int const assert_dummy = (assert(!!pv),0); char unsigned *p = pv, *q = p + (quantity_bytes - 1); for( ; q p; ++p, --q) { unsigned const temp = ByteReversal(*p); *p = ByteReversal(*q); *q = temp; }}int main(void){ unsigned arr[64] = {0,1,2,3,4,5,6,7,8,9, 10,11,12,13,14,15,16,17,18,19, 20,21,22,23,24,25,26,27,28,29, 30,31,32,33,34,35,36,37,38,39, 40,41,42,43,44,45,46,47,48,49, 50,51,52,53,54,55,56,57,58,59, 60,61,62,63}; unsigned const *p, *const q = arr + sizeof arr/sizeof*arr; p = arr; do printf("%u ",*p++); while (p!=q); puts(""); ReverseMemory(arr,sizeof arr); p = arr; do printf("%u ",*p++); while (p!=q); puts(""); ReverseMemory(arr,sizeof arr); p = arr; do printf("%u ",*p++); while (p!=q); puts("");}--Frederick GothamYour "ReverseMemory" function has a small BUG.It cannot work rightly while the "quantity_bytes" parameter is a oddnumber.Here''s my code, point out mistakes please:#include <assert.h>#include <stddef.h>#include <limits.h>#include <stdio.h>#include <stdlib.h>#include <memory.h>// Define the Type of Byte of this Machinetypedef unsigned char Tchar;// Function-pointer for Reverse-functionstypedef Tchar (*ptrRevCharFun)(Tchar);// Define Reverse-functionsTchar RevChar8 (Tchar); // for 8-bit char only// Tchar RevChar16 (Tchar); // if you need// Tchar RevChar32 (Tchar); // if you need///////////////////////////////////////////////// To select a correct function by CHAR_BIT of this machine// If you didn''t define a function for this// machine, you will get a compile-time error#if CHAR_BIT == 8ptrRevCharFun g_pFunRevChar = RevChar8;#endif#if CHAR_BIT == 16ptrRevCharFun g_pFunRevChar = RevChar16; // if you need#endif#if CHAR_BIT == 32ptrRevCharFun g_pFunRevChar = RevChar32; // if you need#endif///////////////////////////////////////////////// Reverse-function for 8-bit char onlyTchar RevChar8 (Tchar value){value = ((value & 0x0fu) << 4) | ((value & 0xf0u) >4);value = ((value & 0x33u) << 2) | ((value & 0xccu) >2);return ((value & 0x55u) << 1) | ((value & 0xaau) >1);}// Memory-Reversevoid RevMemory (Tchar *begin,Tchar *end){Tchar temp;for (end--; begin <= end; ++begin, --end){temp = g_pFunRevChar(*begin);*begin = g_pFunRevChar(*end);*end = temp;}}// For Debug and Testvoid ShowBinChar (Tchar value,Tchar op = '' ''){Tchar mask = 1u << (CHAR_BIT - 1);int i;for (i = 0; i < CHAR_BIT; ++i){if (value & mask) putchar(''1''); else putchar(''0'');value <<= 1;}putchar(op);}// For Debug and Testvoid ShowBinMemory (Tchar *begin,Tchar *end,Tchar op = ''\n''){while (begin != end)ShowBinChar (*begin++);putchar(op);}int main(){Tchar a[] = {''a'', ''b'', ''c'', ''d'', ''e''};ShowBinMemory (a, a + sizeof(a));RevMemory (a, a + sizeof(a));ShowBinMemory (a, a + sizeof(a));}Please refrain from using ALL CAPS -- that is not how English is usuallywritten.Simpy write "table" or "bug", not TABLE or BUG.I''ll have a look over the code when I get the chance.The type of byte on _every_ machine is "unsigned char".You''re forgetting:9-Bit char''s 21-Bit char''s 32-Bit char''s11-Bit char''s 22-Bit char''s 33-Bit char''s12-Bit char''s 23-Bit char''s 34-Bit char''s13-Bit char''s 24-Bit char''s 35-Bit char''s14-Bit char''s 25-Bit char''s 36-Bit char''s15-Bit char''s 26-Bit char''s 37-Bit char''s16-Bit char''s 27-Bit char''s 38-Bit char''s17-Bit char''s 28-Bit char''s 39-Bit char''s18-Bit char''s 29-Bit char''s 40-Bit char''s19-Bit char''s 30-Bit char''s 41-Bit char''s20-Bit char''s 31-Bit char''s 42-Bit char''sAll code posted to comp.lang.c should be fully portable, by which I mean itshould compile and run correctly on any conformaning implementation. Thecode you posted is _not_ fully portable.--Frederick Gotham 这篇关于记忆逆转游戏的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！