/prog/ - [C] explode() — Tinychan BBS

Name: Anonymous 2015-07-29 1:02

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stddef.h>

struct v {
    void *p;
    size_t n;
};

struct v **explode(const void *p, const void *q, size_t pn, size_t qn, size_t size);
void *memmem(const void *p, const void *q, size_t pn, size_t qn, size_t size);
void *memdup(const void *p, size_t n);

int main(void) {
    struct v **p = explode("a b", " ", 3, 1, 1);
    struct v **q = p;
    if(p == NULL) {
        perror(NULL);
        return EXIT_FAILURE;
    }
    while(*p) {
        fwrite((*p)->p, 1, (*p)->n, stdout);
        putchar(' ');
        p++;
    }
    putchar('\n');
    p = q;
    while(*p != NULL) {
        free((*p)->p);
        free(*p++);
    }
    free(q);
    return 0;
}

struct v **explode(const void *p, const void *q, size_t pn, size_t qn, size_t size) {
    void *tmp;
    struct v **rv = NULL;
    size_t i;
    ptrdiff_t j;
    pn *= size;
    qn *= size;
    for(i = 0;; i++) {
        while(pn >= qn && memcmp(p, q, qn) == 0) {
            p = (char *)p + qn;
            pn -= qn;
        }
        if((tmp = realloc(rv, (i + 1) * sizeof *rv)) == NULL) {
            while(i--) {
                free(rv[i]->p);
                free(rv[i]);
            }
            free(rv);
            return NULL;
        }
        rv = tmp;
        rv[i] = NULL;
        if(pn == 0) break;
        if((rv[i] = malloc(sizeof **rv)) == NULL) {
            while(i--) {
                free(rv[i]->p);
                free(rv[i]);
            }
            free(rv);
            return NULL;
        }
        if((tmp = memmem(p, q, pn, qn, size)) == NULL) {
            if((rv[i]->p = memdup(p, pn)) == NULL) {
                while(i--) {
                    free(rv[i]->p);
                    free(rv[i]);
                }
                free(rv);
                return NULL;
            }
            rv[i]->n = pn;
            break;
        }
        else {
            j = (char *)tmp - (char *)p;
            if((tmp = memdup(p, j)) == NULL) {
                while(i--) {
                    free(rv[i]->p);
                    free(rv[i]);
                }
                free(rv);
                return NULL;
            }
            rv[i]->p = tmp;
            rv[i]->n = j;
            p = (char *)p + j;
            pn -= j;
        }
    }
    if(rv[i] != NULL) {
        if((tmp = realloc(rv, (i + 2) * sizeof *rv)) == NULL) {
            i++;
            while(i--) {
                free(rv[i]->p);
                free(rv[i]);
            }
            free(rv);
            return NULL;
        }
        rv[i + 1] = NULL;
    }
    return rv;
}

void *memdup(const void *p, size_t n) {
    void *rv = NULL;
    if((rv = malloc(n)) != NULL) memcpy(rv, p, n);
    return rv;
}

void *memmem(const void *p, const void *q, size_t pn, size_t qn, size_t size) {
    for(; pn >= qn; p = (unsigned char *)p + 1, pn -= size)
    if(memcmp(p, q, qn) == 0) return p;
    return NULL;
}

Name: Cudder !cXCudderUE 2015-07-30 14:37

>>16

; in:
;  esi = source
;  edi = delim
;  edx = source length
;  ecx = delim length
; out:
;  eax = ptr to splits, {ptr,len}, null-terminated, 0 on err
;  all registers change, except esp and ebx
explode:
 mov ebp, esp
 jmp begin_loop
exploop:
 push esi
 push ecx
 push edi
 repnz cmpsb
 pop edi
 pop ecx
 jz match
 pop esi
 inc esi
 dec edx
 jmp loop_cmp
match:
 pop eax
 sub eax, [esp]
 push eax
 sub edx, ecx
begin_loop:
 push esi
loop_cmp:
 cmp ecx, edx
 jbe exploop
expdone:
 push edx
 push 0
 sub ebp, esp
 push ebp
 shr ebp, 2
 call malloc
 test eax, eax
 pop ecx
 jz malerr
 mov ecx, ebp ; not needed if malloc does not modify arg
retloop:
 pop [eax+ecx*4-4]
 loop retloop
malerr:
 ret

One pass through p, and one "reallocation" (try doing that in C!)

[C] explode()

1 Name: Anonymous 2015-07-29 1:02

25 Name: Cudder !cXCudderUE 2015-07-30 14:37

Name: Anonymous 2015-07-29 1:02

Name: Cudder !cXCudderUE 2015-07-30 14:37