ref: 8fdaed8335f3396503838e7403de464f7ebf7211
dir: /ren.c/
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "roff.h"
#define cadj env_adj() /* line buffer */
#define RENWB(wb) ((wb) == &ren_wb) /* is ren_wb */
/* diversions */
struct div {
struct sbuf sbuf; /* diversion output */
int reg; /* diversion register */
int tpos; /* diversion trap position */
int treg; /* diversion trap register */
int dl; /* diversion width */
int prev_d; /* previous \n(.d value */
int prev_h; /* previous \n(.h value */
int prev_mk; /* previous .mk internal register */
int prev_ns; /* previous .ns value */
};
static struct div divs[NPREV]; /* diversion stack */
static struct div *cdiv; /* current diversion */
static int ren_div; /* rendering a diversion */
static int trap_em = -1; /* end macro */
static struct wb ren_wb; /* the main ren.c word buffer */
static int ren_nl; /* just after newline */
static int ren_cnl; /* current char is a newline */
static int ren_unbuf[8]; /* ren_back() buffer */
static int ren_un;
static int ren_fillreq; /* \p request */
static int ren_aborted; /* .ab executed */
static int bp_first = 1; /* prior to the first page */
static int bp_next = 1; /* next page number */
static int bp_count; /* number of pages so far */
static int bp_ejected; /* current ejected page */
static int bp_final; /* 1: executing em, 2: the final page, 3: the 2nd final page */
static int c_fa; /* field delimiter */
static char c_fb[GNLEN]; /* field padding */
static int ren_next(void)
{
return ren_un > 0 ? ren_unbuf[--ren_un] : tr_next();
}
static void ren_back(int c)
{
ren_unbuf[ren_un++] = c;
}
void tr_di(char **args)
{
if (args[1]) {
cdiv = cdiv ? cdiv + 1 : divs;
memset(cdiv, 0, sizeof(*cdiv));
sbuf_init(&cdiv->sbuf);
cdiv->reg = map(args[1]);
cdiv->treg = -1;
if (args[0][2] == 'a' && str_get(cdiv->reg)) /* .da */
sbuf_append(&cdiv->sbuf, str_get(cdiv->reg));
sbuf_printf(&cdiv->sbuf, "%c%s\n", c_cc, TR_DIVBEG);
cdiv->prev_d = n_d;
cdiv->prev_h = n_h;
cdiv->prev_mk = n_mk;
cdiv->prev_ns = n_ns;
n_d = 0;
n_h = 0;
n_mk = 0;
n_ns = 0;
} else if (cdiv) {
sbuf_putnl(&cdiv->sbuf);
sbuf_printf(&cdiv->sbuf, "%c%s\n", c_cc, TR_DIVEND);
str_set(cdiv->reg, sbuf_buf(&cdiv->sbuf));
sbuf_done(&cdiv->sbuf);
n_dl = cdiv->dl;
n_dn = n_d;
n_d = cdiv->prev_d;
n_h = cdiv->prev_h;
n_mk = cdiv->prev_mk;
n_ns = cdiv->prev_ns;
cdiv = cdiv > divs ? cdiv - 1 : NULL;
}
}
int f_divreg(void)
{
return cdiv ? cdiv->reg : -1;
}
int f_hpos(void)
{
return adj_wid(cadj) + wb_wid(&ren_wb);
}
void tr_divbeg(char **args)
{
odiv_beg();
ren_div++;
}
void tr_divend(char **args)
{
odiv_end();
ren_div--;
}
static int trap_reg(int pos);
static int trap_pos(int pos);
static void trap_exec(int reg);
static void ren_page(int pg, int force)
{
if (!force && bp_final >= 2)
return;
n_nl = 0;
n_d = 0;
n_h = 0;
n_pg = pg;
bp_next = n_pg + 1;
bp_count++;
out("p%d\n", pg);
out("V%d\n", 0);
if (trap_pos(-1) == 0)
trap_exec(trap_reg(-1));
}
static void ren_first(void)
{
if (bp_first && !cdiv) {
bp_first = 0;
ren_page(bp_next, 1);
}
}
/* when nodiv, do not append .sp to diversions */
static void ren_sp(int n, int nodiv)
{
ren_first();
/* ignore .sp without arguments when reading diversions */
if (!n && ren_div && !n_u)
return;
n_d += n ? n : n_v;
if (n_d > n_h)
n_h = n_d;
if (cdiv && !nodiv) {
sbuf_putnl(&cdiv->sbuf);
sbuf_printf(&cdiv->sbuf, "%csp %du\n", c_cc, n ? n : n_v);
} else {
n_nl = n_d;
}
}
static void trap_exec(int reg)
{
if (str_get(reg))
in_pushnl(str_get(reg), NULL);
}
static int detect_traps(int beg, int end)
{
int pos = trap_pos(beg);
return pos >= 0 && (cdiv || pos < n_p) && pos <= end;
}
/* return 1 if executed a trap */
static int ren_traps(int beg, int end, int dosp)
{
int pos = trap_pos(beg);
if (detect_traps(beg, end)) {
if (dosp && pos > beg)
ren_sp(pos - beg, 0);
trap_exec(trap_reg(beg));
return 1;
}
return 0;
}
static int detect_pagelimit(int ne)
{
return !cdiv && n_nl + ne >= n_p;
}
/* start a new page if needed */
static int ren_pagelimit(int ne)
{
if (detect_pagelimit(ne)) {
ren_page(bp_next, 0);
return 1;
}
return 0;
}
static void down(int n)
{
if (!ren_traps(n_d, n_d + (n ? n : n_v), 1)) {
ren_sp(n, 0);
ren_pagelimit(0);
}
}
/* flush the given line and send it to out.c */
static void ren_line(char *s, int w, int ad, int ll, int li, int lt)
{
int ljust = lt >= 0 ? lt : li;
int llen = ll - ljust;
n_n = w;
if (ad == AD_C)
ljust += llen > w ? (llen - w) / 2 : 0;
if (ad == AD_R)
ljust += llen - w;
if (cdiv) {
if (cdiv->dl < w)
cdiv->dl = w;
if (ljust)
sbuf_printf(&cdiv->sbuf, "%ch'%du'", c_ec, ljust);
sbuf_append(&cdiv->sbuf, s);
} else {
out("H%d\n", n_o + ljust);
out("V%d\n", n_d);
out_line(s);
}
}
static void ren_transparent(char *s)
{
if (cdiv)
sbuf_printf(&cdiv->sbuf, "%s\n", s);
else
out("%s\n", s);
}
/* return 1 if triggered a trap */
static int ren_bradj(struct adj *adj, int fill, int ad)
{
char cmd[16];
struct sbuf sbuf;
int ll, li, lt, els_neg, els_pos;
int w, prev_d, lspc;
ren_first();
if (!adj_empty(adj, fill)) {
sbuf_init(&sbuf);
w = adj_fill(adj, ad == AD_B, fill, n_hy, &sbuf,
&ll, &li, <, &els_neg, &els_pos);
prev_d = n_d;
if (els_neg)
ren_sp(-els_neg, 1);
if (!n_ns || !sbuf_empty(&sbuf) || els_neg || els_pos) {
ren_sp(0, 0);
ren_line(sbuf_buf(&sbuf), w, ad, ll, li, lt);
n_ns = 0;
}
sbuf_done(&sbuf);
if (els_pos)
ren_sp(els_pos, 1);
n_a = els_pos;
lspc = MAX(1, n_L) * n_v - n_v;
if (detect_traps(prev_d, n_d) || detect_pagelimit(lspc)) {
sprintf(cmd, "%c&", c_ec);
if (!ren_cnl) /* prevent unwanted newlines */
in_push(cmd, NULL);
if (!ren_traps(prev_d, n_d, 0))
ren_pagelimit(lspc);
return 1;
}
if (lspc)
down(lspc);
}
return 0;
}
/* return 1 if triggered a trap */
static int ren_br(int force)
{
return ren_bradj(cadj, !force && !n_ce && n_u,
n_ce ? AD_C : (n_u && !n_na && (n_j != AD_B || !force) ? n_j : AD_L));
}
void tr_br(char **args)
{
if (args[0][0] == c_cc)
ren_br(1);
}
void tr_sp(char **args)
{
int traps = 0;
int n = args[1] ? eval(args[1], 'v') : n_v;
if (args[0][0] == c_cc)
traps = ren_br(1);
if (n && !n_ns && !traps)
down(n);
}
void tr_sv(char **args)
{
int n = eval(args[1], 'v');
n_sv = 0;
if (n_d + n < f_nexttrap())
down(n);
else
n_sv = n;
}
void tr_ns(char **args)
{
n_ns = 1;
}
void tr_rs(char **args)
{
n_ns = 0;
}
void tr_os(char **args)
{
if (n_sv)
down(n_sv);
n_sv = 0;
}
void tr_mk(char **args)
{
if (args[1])
num_set(map(args[1]), n_d);
else
n_mk = n_d;
}
void tr_rt(char **args)
{
int n = args[1] ? eval_re(args[1], n_d, 'v') : n_mk;
if (n >= 0 && n < n_d)
ren_sp(n - n_d, 0);
}
void tr_ne(char **args)
{
int n = args[1] ? eval(args[1], 'v') : n_v;
if (!ren_traps(n_d, n_d + n - 1, 1))
ren_pagelimit(n);
}
static void push_eject(void)
{
char buf[32];
bp_ejected = bp_count;
sprintf(buf, "%c%s %d\n", c_cc, TR_EJECT, bp_ejected);
in_pushnl(buf, NULL);
}
static void push_br(void)
{
char br[8] = {c_cc, 'b', 'r', '\n'};
in_pushnl(br, NULL);
}
static void ren_eject(int id)
{
if (id == bp_ejected && id == bp_count && !cdiv) {
if (detect_traps(n_d, n_p)) {
push_eject();
ren_traps(n_d, n_p, 1);
} else {
bp_ejected = 0;
ren_page(bp_next, 0);
}
}
}
void tr_eject(char **args)
{
ren_eject(atoi(args[1]));
}
void tr_bp(char **args)
{
if (!cdiv && (args[1] || !n_ns)) {
if (bp_ejected != bp_count)
push_eject();
if (args[0][0] == c_cc)
push_br();
if (args[1])
bp_next = eval_re(args[1], n_pg, 0);
}
}
void tr_pn(char **args)
{
if (args[1])
bp_next = eval_re(args[1], n_pg, 0);
}
static void ren_ps(char *s)
{
int ps = !s || !*s || !strcmp("0", s) ? n_s0 : eval_re(s, n_s, 0);
n_s0 = n_s;
n_s = MAX(1, ps);
}
void tr_ps(char **args)
{
ren_ps(args[1]);
}
void tr_ll(char **args)
{
int ll = args[1] ? eval_re(args[1], n_l, 'm') : n_l0;
n_l0 = n_l;
n_l = MAX(0, ll);
adj_ll(cadj, n_l);
}
void tr_in(char **args)
{
int in = args[1] ? eval_re(args[1], n_i, 'm') : n_i0;
if (args[0][0] == c_cc)
ren_br(1);
n_i0 = n_i;
n_i = MAX(0, in);
adj_in(cadj, n_i);
adj_ti(cadj, -1);
}
void tr_ti(char **args)
{
if (args[0][0] == c_cc)
ren_br(1);
if (args[1])
adj_ti(cadj, eval_re(args[1], n_i, 'm'));
}
static void ren_ft(char *s)
{
int fn = !s || !*s || !strcmp("P", s) ? n_f0 : dev_pos(s);
if (fn >= 0) {
n_f0 = n_f;
n_f = fn;
}
}
void tr_ft(char **args)
{
ren_ft(args[1]);
}
void tr_fp(char **args)
{
if (!args[2])
return;
if (dev_mnt(atoi(args[1]), args[2], args[3] ? args[3] : args[2]) < 0)
errmsg("troff: failed to mount %s\n", args[2]);
}
void tr_nf(char **args)
{
if (args[0][0] == c_cc)
ren_br(1);
n_u = 0;
}
void tr_fi(char **args)
{
if (args[0][0] == c_cc)
ren_br(1);
n_u = 1;
}
void tr_ce(char **args)
{
if (args[0][0] == c_cc)
ren_br(1);
n_ce = args[1] ? atoi(args[1]) : 1;
}
void tr_fc(char **args)
{
if (args[1]) {
c_fa = args[1][0];
strcpy(c_fb, args[2] ? args[2] : " ");
} else {
c_fa = -1;
c_fb[0] = '\0';
}
}
static void ren_m(char *s)
{
int m = !s || !*s ? n_m0 : clr_get(s);
n_m0 = n_m;
n_m = m;
}
void tr_ab(char **args)
{
fprintf(stderr, "%s\n", args[1]);
ren_aborted = 1;
}
static void escarg_ren(char *d, int cmd, int (*next)(void), void (*back)(int))
{
char delim[GNLEN];
int c;
if (strchr(ESC_P, cmd)) {
c = next();
if (cmd == 's' && (c == '-' || c == '+')) {
*d++ = c;
c = next();
}
if (c == '(') {
*d++ = next();
*d++ = next();
} else if (!n_cp && c == '[') {
c = next();
while (c > 0 && c != '\n' && c != ']') {
*d++ = c;
c = next();
}
} else {
*d++ = c;
if (cmd == 's' && c >= '1' && c <= '3') {
c = next();
if (isdigit(c))
*d++ = c;
else
back(c);
}
}
}
if (strchr(ESC_Q, cmd)) {
schar_read(delim, next);
while (schar_jump(delim, next, back)) {
if ((c = next()) < 0)
break;
*d++ = c;
}
}
*d = '\0';
}
static int nextchar(char *s, int (*next)(void))
{
int c = next();
int l = utf8len(c);
int i;
if (c < 0)
return 0;
s[0] = c;
for (i = 1; i < l; i++)
s[i] = next();
s[l] = '\0';
return l;
}
static void ren_cmd(struct wb *wb, int c, char *arg)
{
struct glyph *g;
switch (c) {
case ' ':
wb_hmov(wb, charwid(dev_spacewid(), n_s));
break;
case 'b':
ren_bracket(wb, arg);
break;
case 'c':
wb_setpart(wb);
break;
case 'D':
ren_draw(wb, arg);
break;
case 'd':
wb_vmov(wb, SC_EM / 2);
break;
case 'f':
ren_ft(arg);
break;
case 'h':
wb_hmov(wb, eval(arg, 'm'));
break;
case 'k':
num_set(map(arg), RENWB(wb) ? f_hpos() - n_lb : wb_wid(wb));
break;
case 'L':
ren_vline(wb, arg);
break;
case 'l':
ren_hline(wb, arg);
break;
case 'm':
ren_m(arg);
break;
case 'o':
ren_over(wb, arg);
break;
case 'p':
if (RENWB(wb))
ren_fillreq = 1;
break;
case 'r':
wb_vmov(wb, -SC_EM);
break;
case 's':
ren_ps(arg);
break;
case 'u':
wb_vmov(wb, -SC_EM / 2);
break;
case 'v':
wb_vmov(wb, eval(arg, 'v'));
break;
case 'X':
wb_etc(wb, arg);
break;
case 'x':
wb_els(wb, eval(arg, 'v'));
break;
case '0':
g = dev_glyph("0", n_f);
wb_hmov(wb, charwid(g ? g->wid : SC_DW, n_s));
break;
case '|':
wb_hmov(wb, SC_EM / 6);
break;
case '&':
wb_hmov(wb, 0);
break;
case '^':
wb_hmov(wb, SC_EM / 12);
break;
case '{':
case '}':
break;
}
}
static void ren_field(struct wb *wb, int (*next)(void), void (*back)(int));
/* read one character and place it inside wb buffer */
void ren_char(struct wb *wb, int (*next)(void), void (*back)(int))
{
char c[GNLEN * 4];
char arg[ILNLEN];
struct glyph *g;
char *s;
int w, n, l;
nextchar(c, next);
if (c[0] == ' ' || c[0] == '\n') {
wb_put(wb, c);
return;
}
if (c[0] == '\t' || c[0] == '') {
n = RENWB(wb) ? f_hpos() : wb_wid(wb);
wb_hmov(wb, tab_next(n) - n);
return;
}
if (c[0] == c_fa) {
ren_field(wb, next, back);
return;
}
if (c[0] == c_ni)
nextchar(c + 1, next);
if (c[0] == c_ec) {
nextchar(c + 1, next);
if (c[1] == '(') {
l = nextchar(c + 2, next);
l += nextchar(c + 2 + l, next);
c[2 + l] = '\0';
} else if (!n_cp && c[1] == '[') {
l = 0;
n = next();
while (n >= 0 && n != '\n' && n != ']' && l < GNLEN - 1) {
c[l++] = n;
n = next();
}
c[l] = '\0';
} else if (c[1] == 'z') {
w = wb_wid(wb);
ren_char(wb, next, back);
wb_hmov(wb, w - wb_wid(wb));
return;
} else if (c[1] == '!') {
if (ren_nl && next == ren_next) {
s = arg;
n = next();
while (n >= 0 && n != '\n') {
*s++ = n;
n = next();
}
*s = '\0';
ren_transparent(arg);
}
return;
} else if (strchr(" bCcDdfhkLlmNoprsuvXxz0^|{}&", c[1])) {
escarg_ren(arg, c[1], next, back);
if (c[1] == 'N') {
g = dev_glyph_byid(arg, n_f);
c[1] = 'C';
strcpy(arg, g ? g->name : "cnull");
}
if (c[1] != 'C') {
ren_cmd(wb, c[1], arg);
return;
}
strcpy(c, arg);
}
}
if (!n_lg || wb_lig(wb, c)) {
if (n_kn)
wb_kern(wb, c);
wb_put(wb, c);
}
}
/* read the argument of \w and push its width */
int ren_wid(int (*next)(void), void (*back)(int))
{
char delim[GNLEN];
int c, n;
struct wb wb;
wb_init(&wb);
schar_read(delim, next);
odiv_beg();
c = next();
while (c >= 0 && c != '\n') {
back(c);
if (!schar_jump(delim, next, back))
break;
ren_char(&wb, next, back);
c = next();
}
odiv_end();
n = wb_wid(&wb);
wb_wconf(&wb, &n_ct, &n_st, &n_sb);
wb_done(&wb);
return n;
}
/* return 1 if the ending character (ec) was read */
static int ren_until(struct wb *wb, char *delim, int ec,
int (*next)(void), void (*back)(int))
{
int c;
c = next();
while (c >= 0 && c != '\n' && c != ec) {
back(c);
if (!schar_jump(delim, next, back))
break;
ren_char(wb, next, back);
c = next();
}
if (c == '\n')
back(c);
return c == ec;
}
static void wb_cpy(struct wb *dst, struct wb *src, int left)
{
wb_hmov(dst, left - wb_wid(dst));
wb_cat(dst, src);
}
void ren_tl(int (*next)(void), void (*back)(int))
{
struct adj *adj;
struct wb wb, wb2;
char delim[GNLEN];
adj = adj_alloc();
wb_init(&wb);
wb_init(&wb2);
schar_read(delim, next);
/* the left-adjusted string */
ren_until(&wb2, delim, '\n', next, back);
wb_cpy(&wb, &wb2, 0);
/* the centered string */
ren_until(&wb2, delim, '\n', next, back);
wb_cpy(&wb, &wb2, (n_lt - wb_wid(&wb2)) / 2);
/* the right-adjusted string */
ren_until(&wb2, delim, '\n', next, back);
wb_cpy(&wb, &wb2, n_lt - wb_wid(&wb2));
/* flushing the line */
adj_ll(adj, n_lt);
adj_wb(adj, &wb);
adj_nl(adj);
ren_bradj(adj, 0, AD_L);
adj_free(adj);
wb_done(&wb2);
wb_done(&wb);
}
static void ren_field(struct wb *wb, int (*next)(void), void (*back)(int))
{
struct wb wbs[NFIELDS];
int i, n = 0;
int wid = 0;
int left, right, cur_left;
int pad, rem;
while (n < LEN(wbs)) {
wb_init(&wbs[n]);
if (ren_until(&wbs[n++], c_fb, c_fa, next, back))
break;
}
left = RENWB(wb) ? f_hpos() : wb_wid(wb);
right = tab_next(left);
for (i = 0; i < n; i++)
wid += wb_wid(&wbs[i]);
pad = (right - left - wid) / (n > 1 ? n - 1 : 1);
rem = (right - left - wid) % (n > 1 ? n - 1 : 1);
for (i = 0; i < n; i++) {
if (i == 0)
cur_left = left;
else if (i == n - 1)
cur_left = right - wb_wid(&wbs[i]);
else
cur_left = wb_wid(wb) + pad + (i + rem >= n);
wb_cpy(wb, &wbs[i], cur_left);
wb_done(&wbs[i]);
}
}
/* read characters from in.c and pass rendered lines to out.c */
int render(void)
{
struct wb *wb = &ren_wb;
int fillreq;
int c;
n_nl = -1;
wb_init(wb);
tr_first();
ren_first(); /* transition to the first page */
c = ren_next();
while (1) {
if (ren_aborted)
return 1;
if (c < 0) {
if (bp_final >= 2)
break;
if (bp_final == 0 && trap_em >= 0) {
trap_exec(trap_em);
bp_final = 1;
} else {
bp_final = 2;
push_eject();
push_br();
}
c = ren_next();
continue;
}
ren_cnl = c == '\n';
fillreq = 0;
/* add wb (the current word) to cadj */
if (c == ' ' || c == '\n') {
adj_swid(cadj, charwid(dev_spacewid(), n_s));
if (!wb_part(wb)) { /* not after a \c */
adj_wb(cadj, wb);
fillreq = ren_fillreq;
ren_fillreq = 0;
if (c == '\n')
adj_nl(cadj);
else
adj_sp(cadj);
}
}
while ((fillreq && !n_ce && n_u) || adj_full(cadj, !n_ce && n_u)) {
ren_br(0);
fillreq = 0;
}
if (c == '\n' || ren_nl) /* end or start of input line */
n_lb = f_hpos();
if (c == '\n' && !wb_part(wb))
n_ce = MAX(0, n_ce - 1);
if (c != ' ') {
ren_back(c);
ren_char(wb, ren_next, ren_back);
if (c != '\n' && wb_empty(wb))
adj_nonl(cadj);
}
ren_nl = c == '\n';
c = ren_next();
}
bp_final = 3;
if (!adj_empty(cadj, 0))
ren_page(bp_next, 1);
ren_br(1);
wb_done(wb);
return 0;
}
/* trap handling */
#define tposval(i) (tpos[i] < 0 ? n_p + tpos[i] : tpos[i])
static int tpos[NTRAPS]; /* trap positions */
static int treg[NTRAPS]; /* trap registers */
static int ntraps;
static int trap_first(int pos)
{
int best = -1;
int i;
for (i = 0; i < ntraps; i++)
if (treg[i] >= 0 && tposval(i) > pos)
if (best < 0 || tposval(i) < tposval(best))
best = i;
return best;
}
static int trap_byreg(int reg)
{
int i;
for (i = 0; i < ntraps; i++)
if (treg[i] == reg)
return i;
return -1;
}
static int trap_bypos(int reg, int pos)
{
int i;
for (i = 0; i < ntraps; i++)
if (treg[i] >= 0 && tposval(i) == pos)
if (reg == -1 || treg[i] == reg)
return i;
return -1;
}
void tr_wh(char **args)
{
int reg, pos, id;
if (!args[1])
return;
pos = eval(args[1], 'v');
id = trap_bypos(-1, pos);
if (!args[2]) {
if (id >= 0)
treg[id] = -1;
return;
}
reg = map(args[2]);
if (id < 0)
id = trap_byreg(-1);
if (id < 0)
id = ntraps++;
tpos[id] = pos;
treg[id] = reg;
}
void tr_ch(char **args)
{
int reg;
int id;
if (!args[1])
return;
reg = map(args[1]);
id = trap_byreg(reg);
if (id >= 0)
tpos[id] = args[2] ? eval(args[2], 'v') : -1;
}
void tr_dt(char **args)
{
if (!cdiv)
return;
if (args[2]) {
cdiv->tpos = eval(args[1], 'v');
cdiv->treg = map(args[2]);
} else {
cdiv->treg = -1;
}
}
void tr_em(char **args)
{
trap_em = args[1] ? map(args[1]) : -1;
}
static int trap_pos(int pos)
{
int ret = trap_first(pos);
if (bp_final >= 3)
return -1;
if (cdiv)
return cdiv->treg && cdiv->tpos > pos ? cdiv->tpos : -1;
return ret >= 0 ? tposval(ret) : -1;
}
static int trap_reg(int pos)
{
int ret = trap_first(pos);
if (cdiv)
return cdiv->treg && cdiv->tpos > pos ? cdiv->treg : -1;
return ret >= 0 ? treg[ret] : -1;
}
int f_nexttrap(void)
{
int pos = trap_pos(n_d);
if (cdiv)
return pos >= 0 ? pos : 0x7fffffff;
return (pos >= 0 && pos < n_p ? pos : n_p) - n_d;
}