Bitboolbench Solution 1

solution1.c

#include <stdio.h>
#define uint unsigned int

unsigned char toByte(uint b[8])
{
    unsigned char c = 0;
    for(int i=0; i < 8; ++i)
        if(b[i])
            c |= 1 << i;
    return c;
}

void fromByte(unsigned char c, uint b[8])
{
    for(int i=0; i < 8; ++i)
        b[i] = (c & (1<<i)) != 0;
}

int main()
{
        uint i = 0;
        unsigned char by;

        uint bo[8] = {i, i-1, i-2, i-3, i-4, i-5, i-6, i-7}; // set bools
        by = toByte(bo); // bools to byte
        fromByte(by, &bo[8]); // byte to bools

        printf("%c\n", by + bo[0] + bo[1] + bo[2] + bo[3] + bo[4] + bo[5] + bo[6] + bo[7]);
        return 0;
}

/*
toByte:
        push    rbp
        mov     rbp, rsp
        mov     QWORD PTR [rbp-24], rdi
        mov     BYTE PTR [rbp-1], 0
        mov     DWORD PTR [rbp-8], 0
        jmp     .L2
.L4:
        mov     eax, DWORD PTR [rbp-8]
        cdqe
        lea     rdx, [0+rax*4]
        mov     rax, QWORD PTR [rbp-24]
        add     rax, rdx
        mov     eax, DWORD PTR [rax]
        test    eax, eax
        je      .L3
        mov     eax, DWORD PTR [rbp-8]
        mov     edx, 1
        mov     ecx, eax
        sal     edx, cl
        mov     eax, edx
        mov     edx, eax
        movzx   eax, BYTE PTR [rbp-1]
        or      eax, edx
        mov     BYTE PTR [rbp-1], al
.L3:
        add     DWORD PTR [rbp-8], 1
.L2:
        cmp     DWORD PTR [rbp-8], 7
        jle     .L4
        movzx   eax, BYTE PTR [rbp-1]
        pop     rbp
        ret
fromByte:
        push    rbp
        mov     rbp, rsp
        mov     eax, edi
        mov     QWORD PTR [rbp-32], rsi
        mov     BYTE PTR [rbp-20], al
        mov     DWORD PTR [rbp-4], 0
        jmp     .L7
.L8:
        movzx   edx, BYTE PTR [rbp-20]
        mov     eax, DWORD PTR [rbp-4]
        mov     ecx, eax
        sar     edx, cl
        mov     eax, edx
        and     eax, 1
        test    eax, eax
        setne   cl
        mov     eax, DWORD PTR [rbp-4]
        cdqe
        lea     rdx, [0+rax*4]
        mov     rax, QWORD PTR [rbp-32]
        add     rdx, rax
        movzx   eax, cl
        mov     DWORD PTR [rdx], eax
        add     DWORD PTR [rbp-4], 1
.L7:
        cmp     DWORD PTR [rbp-4], 7
        jle     .L8
        nop
        nop
        pop     rbp
        ret
main:
        push    rbp
        mov     rbp, rsp
        sub     rsp, 48
        mov     DWORD PTR [rbp-4], 0

// set bools
        mov     eax, DWORD PTR [rbp-4]
        mov     DWORD PTR [rbp-48], eax
        mov     eax, DWORD PTR [rbp-4]
        sub     eax, 1
        mov     DWORD PTR [rbp-44], eax
        mov     eax, DWORD PTR [rbp-4]
        sub     eax, 2
        mov     DWORD PTR [rbp-40], eax
        mov     eax, DWORD PTR [rbp-4]
        sub     eax, 3
        mov     DWORD PTR [rbp-36], eax
        mov     eax, DWORD PTR [rbp-4]
        sub     eax, 4
        mov     DWORD PTR [rbp-32], eax
        mov     eax, DWORD PTR [rbp-4]
        sub     eax, 5
        mov     DWORD PTR [rbp-28], eax
        mov     eax, DWORD PTR [rbp-4]
        sub     eax, 6
        mov     DWORD PTR [rbp-24], eax
        mov     eax, DWORD PTR [rbp-4]
        sub     eax, 7
        mov     DWORD PTR [rbp-20], eax

// bools to byte
        lea     rax, [rbp-48]
        mov     rdi, rax
        call    toByte
        mov     BYTE PTR [rbp-5], al

// byte to bools
        movzx   eax, BYTE PTR [rbp-5]
        lea     rdx, [rbp-48]
        add     rdx, 32
        mov     rsi, rdx
        mov     edi, eax
        call    fromByte
*/