#include <u.h>

// -------------------------------------------------------------------------
// Dynamic buffer.

/* Grow to particular size */
void*
bufgrow(void* buf, vlong newLen, vlong eltsize)
{
    Assert(bufcap(buf) <= (SIZE_MAX - 1) / 2);

    vlong newCap = MAX(16, MAX(1 + 2 * bufcap(buf), newLen));

    Assert(newLen <= newCap);
    Assert(newCap <= (SIZE_MAX - offsetof(bufHdr, buf)) / eltsize);

    vlong newSize = offsetof(bufHdr, buf) + newCap * eltsize;

    bufHdr* newHdr;
    if (buf) {
        newHdr = _bufHdr(buf);
        newHdr = (bufHdr*)realloc((void*)newHdr, newSize);
    } else {
        newHdr      = (bufHdr*)malloc(newSize);
        newHdr->len = 0;
    }

    newHdr->cap = newCap;
    return (void*)newHdr->buf;
}

/* Pop out a value */
void
_bufpop(void *buf, int i, vlong eltsize)
{
    int n;
    byte *b;
    byte stk[1024];
    Assert(eltsize < sizeof(stk));

    b = (byte*) buf;
    if (n = buflen(buf), i < n) {
        memcpy(stk, b+eltsize*i, eltsize);
        memcpy(b+eltsize*i, b+eltsize*(i+1), eltsize*(n-i-1));
        memcpy(b+eltsize*(n-1), stk, eltsize);
    } 
    _bufHdr(buf)->len--;
}