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#include <kmalloc.h>
#include <buffer.h>
#include <string.h>
#include <sys.h>
// three types of buffers
#define T_BYTES 1
#define T_SLICE 2
#define T_CONCAT 3
struct buffer {
uint16_t rc, type; // takes less space like this
size_t len;
union {
struct {
const char* data;
bool owned;
} bytes;
struct {
struct buffer *buf;
size_t begin;
} slice;
struct {
struct buffer *a, *b;
} concat;
};
};
void buffer_ref(buffer_t *b) {
b->rc++;
}
void buffer_unref(buffer_t *b) {
b->rc--;
if (b->rc == 0) {
switch (b->type) {
case T_BYTES:
if (b->bytes.owned) kfree((void*)b->bytes.data);
break;
case T_SLICE:
buffer_unref(b->slice.buf);
break;
case T_CONCAT:
buffer_unref(b->concat.a);
buffer_unref(b->concat.b);
break;
default:
ASSERT(false);
}
kfree(b);
}
}
size_t buffer_size(buffer_t *b) {
return b->len;
}
size_t read_buffer(buffer_t *b, char* dest, size_t begin, size_t n) {
if (begin >= b->len) return 0;
if (begin + n >= b->len) n = b->len - begin;
switch (b->type) {
case T_BYTES:
memcpy(dest, b->bytes.data + begin, n);
break;
case T_SLICE:
read_buffer(b->slice.buf, dest, begin + b->slice.begin, n);
break;
case T_CONCAT: {
size_t la = b->concat.a->len;
if (begin < la) {
size_t r = read_buffer(b->concat.a, dest, begin, n);
if (r < n) {
ASSERT(read_buffer(b->concat.b, dest, 0, n - r) == n - r);
}
} else {
ASSERT(read_buffer(b->concat.b, dest, begin - la, n) == n);
}
break;
}
default:
ASSERT(false);
}
return n;
}
// ========================= //
// BUFFER CREATION FUNCTIONS //
// ========================= //
buffer_t *buffer_from_bytes_nocopy(const char* data, size_t n) {
buffer_t *b = (buffer_t*)kmalloc(sizeof(buffer_t));
if (b == 0) return 0;
b->rc = 1;
b->type = T_BYTES;
b->len = n;
b->bytes.data = data;
b->bytes.owned = false;
return b;
}
buffer_t *buffer_from_bytes(const char* data, size_t n) {
char* data2 = (char*)kmalloc(n);
if (data2 == 0) return 0;
memcpy(data2, data, n);
buffer_t *b = buffer_from_bytes_nocopy(data2, n);
if (b == 0) {
kfree(data2);
return 0;
}
b->bytes.owned = true;
return b;
}
buffer_t* buffer_slice(buffer_t* src, size_t begin, size_t n) {
if (begin + n > src->len) return 0; // invalid request
buffer_t *b = (buffer_t*)kmalloc(sizeof(buffer_t));
if (b == 0) return 0;
b->rc = 1;
b->type = T_SLICE;
b->len = n;
b->slice.buf = src;
b->slice.begin = begin;
return b;
}
buffer_t* buffer_concat(buffer_t* a, buffer_t* b) {
buffer_t *r = (buffer_t*)kmalloc(sizeof(buffer_t));
if (r == 0) return r;
r->rc = 1;
r->type = T_CONCAT;
r->len = a->len + b->len;
r->concat.a = a;
r->concat.b = b;
return r;
}
buffer_t* buffer_slice_k(buffer_t *b, size_t begin, size_t n) {
buffer_t *r = buffer_slice(b, begin, n);
if (r != 0) {
buffer_ref(b);
}
return r;
}
buffer_t* buffer_concat_k(buffer_t *a, buffer_t *b) {
buffer_t *r = buffer_concat(a, b);
if (r != 0) {
buffer_ref(a);
buffer_ref(b);
}
return r;
}
/* vim: set ts=4 sw=4 tw=0 noet :*/
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