print_internal_uint64_t unrolled

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

typedef union {
    // UINT64_MAX is 20 bytes.
    // 23 bytes of zeros for copying.
    char view_8[20 + 23];
    uint64_t view_64[3];
} Print_Buffer;

void print_internal_uint64_t(uint64_t v) {
    Print_Buffer output = {0};
    size_t i = 0;
    
    //printf("%lu - ", v);
    
    while(true) {
        uint64_t v_next = v / 10000;
        uint64_t vXXXX = v % 10000;
        uint64_t v__XX = vXXXX % 100;
        uint64_t vXX__ = vXXXX / 100;
        uint64_t v___X = v__XX % 10;
        uint64_t v__X_ = v__XX / 10;
        uint64_t v_X__ = vXX__ % 10;
        uint64_t vX___ = vXX__ / 10;
        
        output.view_8[20 - i - 1] = v___X + '0';
        output.view_8[20 - i - 2] = v__X_ + '0';
        output.view_8[20 - i - 3] = v_X__ + '0';
        output.view_8[20 - i - 4] = vX___ + '0';
        
        i += 4;
        v = v_next;
        if(v == 0) {
            break;
        }
    }
    
    for(size_t j = 0; j < 3; ++j) {
        if(output.view_8[20 - i] != '0')
            break;
            
        output.view_8[20 - i] = 0;
        i -= 1;
    }
    
    memmove(&output.view_8[0], &output.view_8[20 - i], 24);
    printf("%s\n", output.view_8);
}

void print_n(uint64_t v) {
    printf("uint64_t: ");
    print_internal_uint64_t(v);
}

void print_n(int64_t v) {
    printf("int64_t: ");
    if(v < 0) {
        printf("-");
        v = -v;
    }
    
    print_internal_uint64_t(v);
}

int main() {
    print_n(1234L);
    print_n(10000L);
    print_n(UINT64_MAX);
    print_n(18446744073709551);
    print_n(0UL);
    print_n(1UL);
    print_n(9UL);
    print_n(50UL);
    print_n(62UL);
    print_n(73L);
    print_n(-84L);
    print_n(99999999L);
    print_n(45645656L);
    print_n(35123123123L);
    print_n(4564565645645656L);
    return 0;
}