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https://github.com/lua/lua
synced 2025-01-21 08:32:03 +03:00
in 'pack'/'unpack', endianness and alignment treated like options +
small changes in names and handling of internal options ('KOption')
This commit is contained in:
Roberto Ierusalimschy
parent
cfa84e1232
commit
57559547a3
107
lstrlib.c
107
lstrlib.c
@ -1,5 +1,5 @@
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/*
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** $Id: lstrlib.c,v 1.203 2014/10/17 10:55:28 roberto Exp roberto $
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** $Id: lstrlib.c,v 1.204 2014/10/17 16:28:21 roberto Exp roberto $
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** Standard library for string operations and pattern-matching
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** See Copyright Notice in lua.h
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*/
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@ -1000,8 +1000,21 @@ typedef struct Header {
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} Header;
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typedef enum KOption {Kint, Kuint, Kfloat, Kchar, Kstring, Kstring0,
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Kspace, Kpadding, Kpaddalig} KOption;
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/*
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** options for pack/unpack
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*/
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typedef enum KOption {
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Kint, /* signed integers */
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Kuint, /* unsigned integers */
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Kfloat, /* floating-point numbers */
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Kchar, /* fixed-length strings */
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Kstring, /* strings with prefixed length */
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Kzstr, /* zero-terminated strings */
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Kpadding, /* padding */
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Kpaddalign, /* padding for alignment */
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Knop, /* no-op (configuration or spaces) */
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Keof /* end of format */
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} KOption;
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/*
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@ -1036,37 +1049,12 @@ static int getnumlimit (Header *h, const char **fmt, int df) {
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/*
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** Reads an option endianness indication ('<'/'>') and
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** returns true if operation should use little endian.
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** Initialize Header
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*/
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static int getendian (const char **fmt) {
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if (**fmt == '<' || **fmt == '>') /* explicit endianness? */
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return (*((*fmt)++) == '<'); /* true iff little endian */
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else /* no endian indication */
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return nativeendian.little; /* use native */
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}
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/*
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** Read and return maximum alignment to be used
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*/
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static int getalignment (Header *h, const char **fmt) {
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if (**fmt == '!') { /* explicit alignment? */
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(*fmt)++; /* skip '!' */
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return getnumlimit(h, fmt, MAXALIGN);
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}
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else
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return 1; /* default is no alignment */
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}
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/*
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** Read optional endianness and alignment indications
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*/
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static void getheader (lua_State *L, Header *h, const char **fmt) {
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static void initheader (lua_State *L, Header *h) {
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h->L = L;
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h->islittle = getendian(fmt);
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h->maxalign = getalignment(h, fmt);
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h->islittle = nativeendian.little;
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h->maxalign = 1;
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}
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@ -1075,6 +1063,7 @@ static void getheader (lua_State *L, Header *h, const char **fmt) {
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*/
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static KOption getoption (Header *h, const char **fmt, int *size) {
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int opt = *((*fmt)++);
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*size = 0; /* default */
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switch (opt) {
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case 'b': *size = sizeof(char); return Kint;
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case 'B': *size = sizeof(char); return Kuint;
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@ -1092,14 +1081,17 @@ static KOption getoption (Header *h, const char **fmt, int *size) {
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case 'I': *size = getnumlimit(h, fmt, sizeof(int)); return Kuint;
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case 's': *size = getnumlimit(h, fmt, sizeof(size_t)); return Kstring;
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case 'c': *size = getnum(fmt, 1); return Kchar;
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case 'z': *size = 0; return Kstring0;
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case 'z': return Kzstr;
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case 'x': *size = 1; return Kpadding;
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case 'X': *size = 0; return Kpaddalig;
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case ' ': *size = 0; return Kspace;
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case 'X': return Kpaddalign;
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case ' ': return Knop;
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case '\0': return Keof;
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case '<': h->islittle = 1; return Knop;
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case '>': h->islittle = 0; return Knop;
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case '!': h->maxalign = getnumlimit(h, fmt, MAXALIGN); return Knop;
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default: {
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*size = 0; /* to avoid warnings */
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luaL_error(h->L, "invalid format option '%c'", opt);
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return (KOption)0;
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return Knop;
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}
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}
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}
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@ -1116,17 +1108,20 @@ static KOption getoption (Header *h, const char **fmt, int *size) {
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*/
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static KOption getdetails (Header *h, size_t totalsize,
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const char **fmt, int *psize, int *ntoalign) {
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KOption opt = getoption(h, fmt, psize);
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int align = *psize; /* usually, alignment follows size */
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if (opt == Kpaddalig) {
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if (**fmt == '\0' || strchr("Xc ", **fmt) != NULL)
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int align;
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KOption opt;
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do {
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opt = getoption(h, fmt, psize);
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} while (opt == Knop); /* skip no-op options */
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align = *psize; /* usually, alignment follows size */
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if (opt == Kpaddalign) { /* 'X' gets alignment from following option */
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if (getoption(h, fmt, &align) == Kchar || align == 0)
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luaL_argerror(h->L, 1, "invalid next option for option 'X'");
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getoption(h, fmt, &align); /* get next element's size for alignment */
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}
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if (align <= 1 || opt == Kchar) /* need no alignment? */
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*ntoalign = 0;
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else {
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if (align > h->maxalign)
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if (align > h->maxalign) /* enforce maximum alignment */
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align = h->maxalign;
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if ((align & (align - 1)) != 0) /* is 'align' not a power of 2? */
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luaL_argerror(h->L, 1, "format asks for alignment not power of 2");
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@ -1173,10 +1168,10 @@ static int str_pack (lua_State *L) {
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const char *fmt = luaL_checkstring(L, 1); /* format string */
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int arg = 1; /* current argument to pack */
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size_t totalsize = 0; /* accumulate total size of result */
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getheader(L, &h, &fmt);
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initheader(L, &h);
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lua_pushnil(L); /* mark to separate arguments from string buffer */
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luaL_buffinit(L, &b);
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while (*fmt != '\0') {
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for (;;) {
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int size, ntoalign;
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KOption opt = getdetails(&h, totalsize, &fmt, &size, &ntoalign);
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totalsize += ntoalign + size;
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@ -1231,7 +1226,7 @@ static int str_pack (lua_State *L) {
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totalsize += len;
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break;
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}
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case Kstring0: { /* zero-terminated string */
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case Kzstr: { /* zero-terminated string */
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size_t len;
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const char *s = luaL_checklstring(L, arg, &len);
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luaL_argcheck(L, strlen(s) == len, arg, "string contains zeros");
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@ -1241,13 +1236,14 @@ static int str_pack (lua_State *L) {
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break;
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}
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case Kpadding: luaL_addchar(&b, '\0'); /* go through */
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case Kpaddalig: case Kspace:
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case Kpaddalign: case Knop:
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arg--; /* undo increment */
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break;
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case Keof: /* end of format */
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luaL_pushresult(&b);
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return 1;
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}
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}
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luaL_pushresult(&b);
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return 1;
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}
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@ -1285,8 +1281,8 @@ static int str_unpack (lua_State *L) {
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size_t pos = (size_t)posrelat(luaL_optinteger(L, 3, 1), ld) - 1;
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int n = 0; /* number of results */
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luaL_argcheck(L, pos <= ld, 3, "initial position out of string");
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getheader(L, &h, &fmt);
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while (*fmt) {
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initheader(L, &h);
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for (;;) {
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int size, ntoalign;
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KOption opt = getdetails(&h, pos, &fmt, &size, &ntoalign);
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if ((size_t)ntoalign + size > ~pos || pos + ntoalign + size > ld)
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@ -1324,20 +1320,21 @@ static int str_unpack (lua_State *L) {
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pos += len;
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break;
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}
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case Kstring0: {
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case Kzstr: {
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size_t len = (int)strlen(data + pos);
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lua_pushlstring(L, data + pos, len);
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pos += len + 1; /* skip final '\0' */
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break;
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}
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case Kpaddalig: case Kpadding: case Kspace:
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case Kpaddalign: case Kpadding: case Knop:
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n--; /* undo increment */
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break;
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case Keof: /* end of format */
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lua_pushinteger(L, pos + 1); /* next position */
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return n;
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}
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pos += size;
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}
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lua_pushinteger(L, pos + 1); /* next position */
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return n + 1;
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}
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/* }====================================================== */
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