String buffer

While reading character data from input stream, buffer used for storing string of arbitrary length is required. lsp_buff_t provides preallocated limited temporary storage which is used as intermediary buffer in construction of string data with arbitrary size.

After initialization with lsp_buff_init, characters are added to buffer with lsp_buff_push function. Once all characters are appended, single string data containing all previously appended characters, can be obtained with lsp_buff_pop function.

Source code

buff.h

#ifndef LISP16_BUFF_H
#define LISP16_BUFF_H

#include "mem.h"
#include "status.h"

#define LSP_BUFF_SIZE 32


typedef struct {
    lsp_mem_t *m;
    lsp_addr_t value;
    lsp_uint8_t buff[LSP_BUFF_SIZE];
    lsp_uint8_t buff_len;
} lsp_buff_t;


void lsp_buff_init(lsp_buff_t *b, lsp_mem_t *m);
lsp_status_t lsp_buff_push(lsp_buff_t *b, lsp_uint8_t c);
lsp_status_t lsp_buff_pop(lsp_buff_t *b, lsp_addr_t *value);
void lsp_buff_clear(lsp_buff_t *b);

#endif

buff.c

#include "buff.h"


static lsp_status_t update_str(lsp_buff_t *b) {
    lsp_uint16_t value_len =
        ((b->value == b->m->nil) ? 0 : lsp_mem_get_string_len(b->m, b->value));

    lsp_addr_t value;
    lsp_status_t status =
        lsp_mem_create_string(b->m, value_len + b->buff_len, &value);
    if (status != LSP_SUCCESS)
        return status;

    for (lsp_uint16_t i = 0; i < value_len; ++i)
        lsp_mem_set_string_data(b->m, value, i,
                                lsp_mem_get_string_data(b->m, b->value, i));

    for (lsp_uint16_t i = 0; i < b->buff_len; ++i)
        lsp_mem_set_string_data(b->m, value, i + value_len, b->buff[i]);

    lsp_mem_dec_ref(b->m, b->value);
    b->value = value;
    b->buff_len = 0;
    return LSP_SUCCESS;
}


void lsp_buff_init(lsp_buff_t *b, lsp_mem_t *m) {
    b->m = m;
    b->value = m->nil;
    b->buff_len = 0;
}


lsp_status_t lsp_buff_push(lsp_buff_t *b, lsp_uint8_t c) {
    if (b->buff_len + 1 >= LSP_BUFF_SIZE) {
        lsp_status_t status = update_str(b);
        if (status != LSP_SUCCESS)
            return status;
    }

    b->buff[b->buff_len++] = c;
    return LSP_SUCCESS;
}


lsp_status_t lsp_buff_pop(lsp_buff_t *b, lsp_addr_t *value) {
    lsp_status_t status = update_str(b);
    if (status != LSP_SUCCESS)
        return status;

    *value = b->value;
    b->value = b->m->nil;
    return LSP_SUCCESS;
}


void lsp_buff_clear(lsp_buff_t *b) {
    lsp_mem_dec_ref(b->m, b->value);
    b->value = b->m->nil;
}