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  1. #include <stdint.h>
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4.  
  5. // A helper function, which is performed very very rare.
  6. void SaveCode (const uint8_t length, const uint64_t code);
  7.  
  8.  
  9. int main (int argc, char * argv [])
  10. {
  11.     const uint8_t  sideLobeLimit=  1;
  12.     const uint8_t  length       = 13;
  13.     const uint64_t beginCode    =  1ull << (length  - 1);
  14.     const uint64_t endCode      = (1ull <<  length) - 1;
  15.     const uint64_t mask         = (1ull << (length  - 1) ) - 1ull;
  16.  
  17.     __asm__ __volatile__ (
  18.     "INIT:                          \n\t" // Prepare for computation.
  19.     "    xorq    %%r8,       %%r8   \n\t"
  20.     "    movb    %[length],  %%r8b  \n\t" //     Load length of sequences into CPU register.
  21.     "    movq    %[code],    %%r9   \n\t" //     Load first sequence of the range into CPU register.
  22.     "    movq    %[maxcode], %%r10  \n\t" //     Load last sequence of the range into CPU register.
  23.     "    movb    %[limit],   %%r11b \n\t" //     Load maximum allowed level of sidelobes into CPU register.
  24.     "    movq    %[mask],    %%r12  \n\t" //     Load mask for extracting significant bits into CPU register.
  25.     "CHECK_CODE:                    \n\t" // Body of loop through sequence (like the "do-while" loop).
  26.     "    mov     $1,         %%cx   \n\t" //     Set the offset value.
  27.     "    movq    %%r12,      %%r13  \n\t" //     Set mask into mutable variable.
  28.     "NEXT_SHIFT:                    \n\t" //     Beginning of loop through shift of sequence (like the "do-while" loop).
  29.     "    movq    %%r9,       %%rdi  \n\t" //         Shifting sequence.
  30.     "    shrq    %%cl,       %%rdi  \n\t" //         Shift.
  31.     "    xorq    %%r9,       %%rdi  \n\t" //         Counting level of sidelobes.
  32.     "    andq    %%r13,      %%rdi  \n\t" //             Remove extra bits.
  33.     "    popcntq %%rdi,      %%rax  \n\t" //             al =         n         (number of the different bits).
  34.     "    shl     $1,         %%ax   \n\t" //             al =     2 * n.
  35.     "    sub     %%r8w,      %%ax   \n\t" //             al =     2 * n - l     (l - length of the sequence).
  36.     "    add     %%cx,       %%ax   \n\t" //             al = o + 2 * n - l     (o - current offset).
  37.     "    cwd                        \n\t" //             .
  38.     "    add     %%dx,       %%ax   \n\t" //             .
  39.     "    xor     %%dx,       %%ax   \n\t" //             al =|o + 2 * n - l|    (now al contain the sidelobe level).
  40.     "    cmpb    %%r11b,     %%al   \n\t" //         Check if the sidelobe level acceptable?
  41.     "    jg      NEXT_CODE          \n\t" //             If it is not, then go to the next sequence.
  42.     "    incb    %%cl               \n\t" //         Increment the offset for creating next shifted sequence.
  43.     "    cmpb    %%cl,       %%r8b  \n\t" //         Check if is it the lass offset.
  44.     "    jbe     SAVE_CODE          \n\t" //             If it is, then save cureent sequence.
  45.     "    shrq    $1,         %%r13  \n\t" //         Shift mask for next shifted sequence.
  46.     "    jmp     NEXT_SHIFT         \n\t" //     End of loop through shift of sequence.
  47.     "NEXT_CODE:                     \n\t" // Control of loop through sequence.
  48.     "    incq    %%r9               \n\t" //     Set next sequence.
  49.     "    cmpq    %%r10,      %%r9   \n\t" //     Check if the sequence inside the range.
  50.     "    jbe     CHECK_CODE         \n\t" //         If it is, then go to the begining of the loops body.
  51.     "    jmp     QUIT               \n\t" //         If it is not, then go to the end of procedure.
  52.     "SAVE_CODE:                     \n\t" // Saving sequence with accepted level of sidelobes.
  53.     "    pushq   %%r8               \n\t" //     Store registers.
  54.     "    pushq   %%r9               \n\t" //     .
  55.     "    pushq   %%r10              \n\t" //     .
  56.     "    pushq   %%r11              \n\t" //     .
  57.     "    pushq   %%r12              \n\t" //     .
  58.     "    movl    %%r8d,      %%edi  \n\t" //     .
  59.     "    movq    %%r9,       %%rsi  \n\t" //     .
  60.     "    call    SaveCode           \n\t" //     Calling external function for saving the sequence.
  61.     "    popq    %%r12              \n\t" //     Restore registers.
  62.     "    popq    %%r11              \n\t" //     .
  63.     "    popq    %%r10              \n\t" //     .
  64.     "    popq    %%r9               \n\t" //     .
  65.     "    popq    %%r8               \n\t" //     .
  66.     "    jmp     NEXT_CODE          \n\t" //     Continue test sequences.
  67.     "QUIT:                          \n\t" // Exit of procedure.
  68.     "    nop                        \n\t" // .
  69.     :
  70.     : [length ] "m" (length),
  71.       [code   ] "m" (beginCode),
  72.       [maxcode] "m" (endCode),
  73.       [limit  ] "m" (sideLobeLimit),
  74.       [mask   ] "m" (mask)
  75.     : "%rax", "%rcx", "%rdx", "%rdi", "%rsi",
  76.       "%r8",  "%r9",  "%r10", "%r11", "%r12", "%r13"
  77.     );
  78.  
  79.     return EXIT_SUCCESS;
  80. }
  81.  
  82.  
  83. void SaveCode (const uint8_t length, const uint64_t code)
  84. {
  85.     uint8_t i = 0;
  86.     for (i = 0; i < length; ++i) {
  87.         (code >> i) & 0x01 ? printf ("+") : printf ("-");
  88.     }
  89.     printf ("\n");
  90. }
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin
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Standard input is empty
compilation info 
prog.cpp: In function ‘int main(int, char**)’:
prog.cpp:77:6: error: unknown register name ‘%r13’ in ‘asm’
     );
      ^
prog.cpp:77:6: error: unknown register name ‘%r12’ in ‘asm’
prog.cpp:77:6: error: unknown register name ‘%r11’ in ‘asm’
prog.cpp:77:6: error: unknown register name ‘%r10’ in ‘asm’
prog.cpp:77:6: error: unknown register name ‘%r9’ in ‘asm’
prog.cpp:77:6: error: unknown register name ‘%r8’ in ‘asm’
stdout
copy 
Standard output is empty
https://ideone.com/j66WbK
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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