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cbprintf_complete.c
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/*
* Copyright (c) 1997-2010, 2012-2015 Wind River Systems, Inc.
* Copyright (c) 2020 Nordic Semiconductor ASA
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <ctype.h>
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <toolchain.h>
#include <sys/types.h>
#include <sys/util.h>
#include <sys/cbprintf.h>
/* newlib doesn't declare this function unless __POSIX_VISIBLE >= 200809. No
* idea how to make that happen, so lets put it right here.
*/
size_t strnlen(const char *s, size_t maxlen);
/* Provide typedefs used for signed and unsigned integral types
* capable of holding all convertible integral values.
*/
#ifdef CONFIG_CBPRINTF_FULL_INTEGRAL
typedef intmax_t sint_value_type;
typedef uintmax_t uint_value_type;
#else
typedef int32_t sint_value_type;
typedef uint32_t uint_value_type;
#endif
/* The maximum buffer size required is for octal formatting: one character for
* every 3 bits. Neither EOS nor alternate forms are required.
*/
#define CONVERTED_INT_BUFLEN ((CHAR_BIT * sizeof(uint_value_type) + 2) / 3)
/* The float code may extract up to 16 digits, plus a prefix, a
* leading 0, a dot, and an exponent in the form e+xxx for a total of
* 24. Add a trailing NULL so the buffer length required is 25.
*/
#define CONVERTED_FP_BUFLEN 25U
#ifdef CONFIG_CBPRINTF_FP_SUPPORT
#define CONVERTED_BUFLEN MAX(CONVERTED_INT_BUFLEN, CONVERTED_FP_BUFLEN)
#else
#define CONVERTED_BUFLEN CONVERTED_INT_BUFLEN
#endif
/* The allowed types of length modifier. */
enum length_mod_enum {
LENGTH_NONE, /* int */
LENGTH_HH, /* char */
LENGTH_H, /* short */
LENGTH_L, /* long */
LENGTH_LL, /* long long */
LENGTH_J, /* intmax */
LENGTH_Z, /* size_t */
LENGTH_T, /* ptrdiff_t */
LENGTH_UPPER_L, /* long double */
};
/* Categories of conversion specifiers. */
enum specifier_cat_enum {
/* unrecognized */
SPECIFIER_INVALID,
/* d, i */
SPECIFIER_SINT,
/* c, o, u, x, X */
SPECIFIER_UINT,
/* n, p, s */
SPECIFIER_PTR,
/* a, A, e, E, f, F, g, G */
SPECIFIER_FP,
};
#define CHAR_IS_SIGNED (CHAR_MIN != 0)
#if CHAR_IS_SIGNED
#define CASE_SINT_CHAR case 'c':
#define CASE_UINT_CHAR
#else
#define CASE_SINT_CHAR
#define CASE_UINT_CHAR case 'c':
#endif
/* We need two pieces of information about wchar_t:
* * WCHAR_IS_SIGNED: whether it's signed or unsigned;
* * WINT_TYPE: the type to use when extracting it from va_args
*
* The former can be determined from the value of WCHAR_MIN if it's defined.
* It's not for minimal libc, so treat it as whatever char is.
*
* The latter should be wint_t, but minimal libc doesn't provide it. We can
* substitute wchar_t as long as that type does not undergo default integral
* promotion as an argument. But it does for at least one toolchain (xtensa),
* and where it does we need to use the promoted type in va_arg() to avoid
* build errors, otherwise we can use the base type. We can tell that
* integral promotion occurs if WCHAR_MAX is strictly less than INT_MAX.
*/
#ifndef WCHAR_MIN
#define WCHAR_IS_SIGNED CHAR_IS_SIGNED
#if WCHAR_IS_SIGNED
#define WINT_TYPE int
#else /* wchar signed */
#define WINT_TYPE unsigned int
#endif /* wchar signed */
#else /* WCHAR_MIN defined */
#define WCHAR_IS_SIGNED ((WCHAR_MIN - 0) != 0)
#if WCHAR_MAX < INT_MAX
/* Signed or unsigned, it'll be int */
#define WINT_TYPE int
#else /* wchar rank vs int */
#define WINT_TYPE wchar_t
#endif /* wchar rank vs int */
#endif /* WCHAR_MIN defined */
/* Case label to identify conversions for signed integral values. The
* corresponding argument_value tag is sint and category is
* SPECIFIER_SINT.
*/
#define SINT_CONV_CASES \
'd': \
CASE_SINT_CHAR \
case 'i'
/* Case label to identify conversions for signed integral arguments.
* The corresponding argument_value tag is uint and category is
* SPECIFIER_UINT.
*/
#define UINT_CONV_CASES \
'o': \
CASE_UINT_CHAR \
case 'u': \
case 'x': \
case 'X'
/* Case label to identify conversions for floating point arguments.
* The corresponding argument_value tag is either dbl or ldbl,
* depending on length modifier, and the category is SPECIFIER_FP.
*/
#define FP_CONV_CASES \
'a': \
case 'A': \
case 'e': \
case 'E': \
case 'f': \
case 'F': \
case 'g': \
case 'G'
/* Case label to identify conversions for pointer arguments. The
* corresponding argument_value tag is ptr and the category is
* SPECIFIER_PTR.
*/
#define PTR_CONV_CASES \
'n': \
case 'p': \
case 's'
/* Storage for an argument value. */
union argument_value {
/* For SINT conversions */
sint_value_type sint;
/* For UINT conversions */
uint_value_type uint;
/* For FP conversions without L length */
double dbl;
/* For FP conversions with L length */
long double ldbl;
/* For PTR conversions */
void *ptr;
};
/* Structure capturing all attributes of a conversion
* specification.
*
* Initial values come from the specification, but are updated during
* the conversion.
*/
struct conversion {
/** Indicates flags are inconsistent */
bool invalid: 1;
/** Indicates flags are valid but not supported */
bool unsupported: 1;
/** Left-justify value in width */
bool flag_dash: 1;
/** Explicit sign */
bool flag_plus: 1;
/** Space for non-negative sign */
bool flag_space: 1;
/** Alternative form */
bool flag_hash: 1;
/** Pad with leading zeroes */
bool flag_zero: 1;
/** Width field present */
bool width_present: 1;
/** Width value from int argument
*
* width_value is set to the absolute value of the argument.
* If the argument is negative flag_dash is also set.
*/
bool width_star: 1;
/** Precision field present */
bool prec_present: 1;
/** Precision from int argument
*
* prec_value is set to the value of a non-negative argument.
* If the argument is negative prec_present is cleared.
*/
bool prec_star: 1;
/** Length modifier (value from length_mod_enum) */
unsigned int length_mod: 4;
/** Indicates an a or A conversion specifier.
*
* This affects how precision is handled.
*/
bool specifier_a: 1;
/** Conversion specifier category (value from specifier_cat_enum) */
unsigned int specifier_cat: 3;
/** If set alternate form requires 0 before octal. */
bool altform_0: 1;
/** If set alternate form requires 0x before hex. */
bool altform_0c: 1;
/** Set when pad0_value zeroes are to be to be inserted after
* the decimal point in a floating point conversion.
*/
bool pad_postdp: 1;
/** Set for floating point values that have a non-zero
* pad0_prefix or pad0_pre_exp.
*/
bool pad_fp: 1;
/** Conversion specifier character */
unsigned char specifier;
union {
/** Width value from specification.
*
* Valid until conversion begins.
*/
int width_value;
/** Number of extra zeroes to be inserted around a
* formatted value:
*
* * before a formatted integer value due to precision
* and flag_zero; or
* * before a floating point mantissa decimal point
* due to precision; or
* * after a floating point mantissa decimal point due
* to precision.
*
* For example for zero-padded hexadecimal integers
* this would insert where the angle brackets are in:
* 0x<>hhhh.
*
* For floating point numbers this would insert at
* either <1> or <2> depending on #pad_postdp:
* VVV<1>.<2>FFFFeEEE
*
* Valid after conversion begins.
*/
int pad0_value;
};
union {
/** Precision from specification.
*
* Valid until conversion begins.
*/
int prec_value;
/** Number of extra zeros to be inserted after a decimal
* point due to precision.
*
* Inserts at <> in: VVVV.FFFF<>eEE
*
* Valid after conversion begins.
*/
int pad0_pre_exp;
};
};
/** Get a size represented as a sequence of decimal digits.
*
* @param[inout] str where to read from. Updated to point to the first
* unconsumed character. There must be at least one non-digit character in
* the referenced text.
*
* @return the decoded integer value.
*/
static size_t extract_decimal(const char **str)
{
const char *sp = *str;
size_t val = 0;
while (isdigit((int)(unsigned char)*sp)) {
val = 10U * val + *sp++ - '0';
}
*str = sp;
return val;
}
/** Extract C99 conversion specification flags.
*
* @param conv pointer to the conversion being defined.
*
* @param sp pointer to the first character after the % of a conversion
* specifier.
*
* @return a pointer the first character that follows the flags.
*/
static inline const char *extract_flags(struct conversion *conv,
const char *sp)
{
bool loop = true;
do {
switch (*sp) {
case '-':
conv->flag_dash = true;
break;
case '+':
conv->flag_plus = true;
break;
case ' ':
conv->flag_space = true;
break;
case '#':
conv->flag_hash = true;
break;
case '0':
conv->flag_zero = true;
break;
default:
loop = false;
}
if (loop) {
++sp;
}
} while (loop);
/* zero && dash => !zero */
if (conv->flag_zero && conv->flag_dash) {
conv->flag_zero = false;
}
/* space && plus => !plus, handled in emitter code */
return sp;
}
/** Extract a C99 conversion specification width.
*
* @param conv pointer to the conversion being defined.
*
* @param sp pointer to the first character after the flags element of a
* conversion specification.
*
* @return a pointer the first character that follows the width.
*/
static inline const char *extract_width(struct conversion *conv,
const char *sp)
{
conv->width_present = true;
if (*sp == '*') {
conv->width_star = true;
return ++sp;
}
const char *wp = sp;
size_t width = extract_decimal(&sp);
if (sp != wp) {
conv->width_present = true;
conv->width_value = width;
conv->unsupported |= ((conv->width_value < 0)
|| (width != (size_t)conv->width_value));
}
return sp;
}
/** Extract a C99 conversion specification precision.
*
* @param conv pointer to the conversion being defined.
*
* @param sp pointer to the first character after the width element of a
* conversion specification.
*
* @return a pointer the first character that follows the precision.
*/
static inline const char *extract_prec(struct conversion *conv,
const char *sp)
{
conv->prec_present = (*sp == '.');
if (!conv->prec_present) {
return sp;
}
++sp;
if (*sp == '*') {
conv->prec_star = true;
return ++sp;
}
size_t prec = extract_decimal(&sp);
conv->prec_value = prec;
conv->unsupported |= ((conv->prec_value < 0)
|| (prec != (size_t)conv->prec_value));
return sp;
}
/** Extract a C99 conversion specification length.
*
* @param conv pointer to the conversion being defined.
*
* @param sp pointer to the first character after the precision element of a
* conversion specification.
*
* @return a pointer the first character that follows the precision.
*/
static inline const char *extract_length(struct conversion *conv,
const char *sp)
{
switch (*sp) {
case 'h':
if (*++sp == 'h') {
conv->length_mod = LENGTH_HH;
++sp;
} else {
conv->length_mod = LENGTH_H;
}
break;
case 'l':
if (*++sp == 'l') {
conv->length_mod = LENGTH_LL;
++sp;
} else {
conv->length_mod = LENGTH_L;
}
break;
case 'j':
conv->length_mod = LENGTH_J;
++sp;
break;
case 'z':
conv->length_mod = LENGTH_Z;
++sp;
break;
case 't':
conv->length_mod = LENGTH_T;
++sp;
break;
case 'L':
conv->length_mod = LENGTH_UPPER_L;
++sp;
/* We recognize and consume these, but can't format
* them.
*/
conv->unsupported = true;
break;
default:
conv->length_mod = LENGTH_NONE;
break;
}
return sp;
}
/* Extract a C99 conversion specifier.
*
* This is the character that identifies the representation of the converted
* value.
*
* @param conv pointer to the conversion being defined.
*
* @param sp pointer to the first character after the length element of a
* conversion specification.
*
* @return a pointer the first character that follows the specifier.
*/
static inline const char *extract_specifier(struct conversion *conv,
const char *sp)
{
bool unsupported = false;
conv->specifier = *sp++;
switch (conv->specifier) {
case SINT_CONV_CASES:
conv->specifier_cat = SPECIFIER_SINT;
goto int_conv;
case UINT_CONV_CASES:
conv->specifier_cat = SPECIFIER_UINT;
int_conv:
/* L length specifier not acceptable */
if (conv->length_mod == LENGTH_UPPER_L) {
conv->invalid = true;
}
/* For c LENGTH_NONE and LENGTH_L would be ok,
* but we don't support formatting wide characters.
*/
if (conv->specifier == 'c') {
unsupported = (conv->length_mod != LENGTH_NONE);
} else if (!IS_ENABLED(CONFIG_CBPRINTF_FULL_INTEGRAL)) {
/* Disable conversion that might produce truncated
* results with buffers sized for 32 bits.
*/
switch (conv->length_mod) {
case LENGTH_L:
unsupported = sizeof(long) > 4;
break;
case LENGTH_LL:
unsupported = sizeof(long long) > 4;
break;
case LENGTH_J:
unsupported = sizeof(uintmax_t) > 4;
break;
case LENGTH_Z:
unsupported = sizeof(size_t) > 4;
break;
case LENGTH_T:
unsupported = sizeof(ptrdiff_t) > 4;
break;
default:
/* Add an empty default with break, this is a defensive
* programming. Static analysis tool won't raise a violation
* if default is empty, but has that comment.
*/
break;
}
} else {
;
}
break;
case FP_CONV_CASES:
conv->specifier_cat = SPECIFIER_FP;
/* Don't support if disabled */
if (!IS_ENABLED(CONFIG_CBPRINTF_FP_SUPPORT)) {
unsupported = true;
break;
}
/* When FP enabled %a support is still conditional. */
conv->specifier_a = (conv->specifier == 'a')
|| (conv->specifier == 'A');
if (conv->specifier_a
&& !IS_ENABLED(CONFIG_CBPRINTF_FP_A_SUPPORT)) {
unsupported = true;
break;
}
/* The l specifier has no effect. Otherwise length
* modifiers other than L are invalid.
*/
if (conv->length_mod == LENGTH_L) {
conv->length_mod = LENGTH_NONE;
} else if ((conv->length_mod != LENGTH_NONE)
&& (conv->length_mod != LENGTH_UPPER_L)) {
conv->invalid = true;
} else {
;
}
break;
/* PTR cases are distinct */
case 'n':
conv->specifier_cat = SPECIFIER_PTR;
/* Anything except L */
if (conv->length_mod == LENGTH_UPPER_L) {
unsupported = true;
}
break;
case 's':
case 'p':
conv->specifier_cat = SPECIFIER_PTR;
/* p: only LENGTH_NONE
*
* s: LENGTH_NONE or LENGTH_L but wide
* characters not supported.
*/
if (conv->length_mod != LENGTH_NONE) {
unsupported = true;
}
break;
default:
conv->invalid = true;
break;
}
conv->unsupported |= unsupported;
return sp;
}
/* Extract the complete C99 conversion specification.
*
* @param conv pointer to the conversion being defined.
*
* @param sp pointer to the % that introduces a conversion specification.
*
* @return pointer to the first character that follows the specification.
*/
static inline const char *extract_conversion(struct conversion *conv,
const char *sp)
{
*conv = (struct conversion) {
.invalid = false,
};
/* Skip over the opening %. If the conversion specifier is %,
* that's the only thing that should be there, so
* fast-exit.
*/
++sp;
if (*sp == '%') {
conv->specifier = *sp++;
return sp;
}
sp = extract_flags(conv, sp);
sp = extract_width(conv, sp);
sp = extract_prec(conv, sp);
sp = extract_length(conv, sp);
sp = extract_specifier(conv, sp);
return sp;
}
#ifdef CONFIG_64BIT
static void _ldiv5(uint64_t *v)
{
/* The compiler can optimize this on its own on 64-bit architectures */
*v /= 5U;
}
#else /* CONFIG_64BIT */
/*
* Tiny integer divide-by-five routine. The full 64 bit division
* implementations in libgcc are very large on some architectures, and
* currently nothing in Zephyr pulls it into the link. So it makes
* sense to define this much smaller special case here to avoid
* including it just for printf.
*
* It works by multiplying v by the reciprocal of 5 i.e.:
*
* result = v * ((1 << 64) / 5) / (1 << 64)
*
* This produces a 128-bit result, but we drop the bottom 64 bits which
* accounts for the division by (1 << 64). The product is kept to 64 bits
* by summing partial multiplications and shifting right by 32 which on
* most 32-bit architectures means only a register drop.
*
* Here the multiplier is: (1 << 64) / 5 = 0x3333333333333333
* i.e. a 62 bits value. To compensate for the reduced precision, we
* add an initial bias of 1 to v. This conveniently allows for keeping
* the multiplier in a single 32-bit register given its pattern.
* Enlarging the multiplier to 64 bits would also work but carry handling
* on the summing of partial mults would be necessary, and a final right
* shift would be needed, requiring more instructions.
*/
static void _ldiv5(uint64_t *v)
{
uint32_t v_lo = *v;
uint32_t v_hi = *v >> 32;
uint32_t m = 0x33333333;
uint64_t result;
/*
* Force the multiplier constant into a register and make it
* opaque to the compiler, otherwise gcc tries to be too smart
* for its own good with a large expansion of adds and shifts.
*/
__asm__ ("" : "+r" (m));
/*
* Apply a bias of 1 to v. We can't add it to v as this would overflow
* it when at max range. Factor it out with the multiplier upfront.
*/
result = ((uint64_t)m << 32) | m;
/* The actual multiplication. */
result += (uint64_t)v_lo * m;
result >>= 32;
result += (uint64_t)v_lo * m;
result += (uint64_t)v_hi * m;
result >>= 32;
result += (uint64_t)v_hi * m;
*v = result;
}
#endif /* CONFIG_64BIT */
/* Division by 10 */
static void _ldiv10(uint64_t *v)
{
*v >>= 1;
_ldiv5(v);
}
/* Extract the next decimal character in the converted representation of a
* fractional component.
*/
static char _get_digit(uint64_t *fr, int *digit_count)
{
char rval;
if (*digit_count > 0) {
--*digit_count;
*fr *= 10U;
rval = ((*fr >> 60) & 0xF) + '0';
*fr &= (BIT64(60) - 1U);
} else {
rval = '0';
}
return rval;
}
static inline size_t conversion_radix(char specifier)
{
switch (specifier) {
default:
case 'd':
case 'i':
case 'u':
return 10;
case 'o':
return 8;
case 'p':
case 'x':
case 'X':
return 16;
}
}
/* Writes the given value into the buffer in the specified base.
*
* Precision is applied *ONLY* within the space allowed.
*
* Alternate form value is applied to o, x, and X conversions.
*
* The buffer is filled backwards, so the input bpe is the end of the
* generated representation. The returned pointer is to the first
* character of the representation.
*/
static char *encode_uint(uint_value_type value,
struct conversion *conv,
char *bps,
const char *bpe)
{
bool upcase = isupper((int)conv->specifier);
const unsigned int radix = conversion_radix(conv->specifier);
char *bp = bps + (bpe - bps);
do {
unsigned int lsv = (unsigned int)(value % radix);
*--bp = (lsv <= 9) ? ('0' + lsv)
: upcase ? ('A' + lsv - 10) : ('a' + lsv - 10);
value /= radix;
} while ((value != 0) && (bps < bp));
/* Record required alternate forms. This can be determined
* from the radix without re-checking specifier.
*/
if (conv->flag_hash) {
if (radix == 8) {
conv->altform_0 = true;
} else if (radix == 16) {
conv->altform_0c = true;
} else {
;
}
}
return bp;
}
/* Number of bits in the fractional part of an IEEE 754-2008 double
* precision float.
*/
#define FRACTION_BITS 52
/* Number of hex "digits" in the fractional part of an IEEE 754-2008
* double precision float.
*/
#define FRACTION_HEX ceiling_fraction(FRACTION_BITS, 4)
/* Number of bits in the exponent of an IEEE 754-2008 double precision
* float.
*/
#define EXPONENT_BITS 11
/* Mask for the sign (negative) bit of an IEEE 754-2008 double precision
* float.
*/
#define SIGN_MASK BIT64(63)
/* Mask for the high-bit of a uint64_t representation of a fractional
* value.
*/
#define BIT_63 BIT64(63)
/* Convert the IEEE 754-2008 double to text format.
*
* @param value the 64-bit floating point value.
*
* @param conv details about how the conversion is to proceed. Some fields
* are adjusted based on the value being converted.
*
* @param precision the precision for the conversion (generally digits past
* the decimal point).
*
* @param bps pointer to the first character in a buffer that will hold the
* converted value.
*
* @param bpe On entry this points to the end of the buffer reserved to hold
* the converted value. On exit it is updated to point just past the
* converted value.
*
* return a pointer to the start of the converted value. This may not be @p
* bps but will be consistent with the exit value of *bpe.
*/
static char *encode_float(double value,
struct conversion *conv,
int precision,
char *sign,
char *bps,
const char **bpe)
{
union {
uint64_t u64;
double dbl;
} u = {
.dbl = value,
};
bool prune_zero = false;
char *buf = bps;
/* Prepend the sign: '-' if negative, flags control
* non-negative behavior.
*/
if ((u.u64 & SIGN_MASK) != 0U) {
*sign = '-';
} else if (conv->flag_plus) {
*sign = '+';
} else if (conv->flag_space) {
*sign = ' ';
} else {
;
}
/* Extract the non-negative offset exponent and fraction. Record
* whether the value is subnormal.
*/
char c = conv->specifier;
int expo = (u.u64 >> FRACTION_BITS) & BIT_MASK(EXPONENT_BITS);
uint64_t fract = u.u64 & BIT64_MASK(FRACTION_BITS);
bool is_subnormal = (expo == 0) && (fract != 0);
/* Exponent of all-ones signals infinity or NaN, which are
* text constants regardless of specifier.
*/
if (expo == BIT_MASK(EXPONENT_BITS)) {
if (fract == 0) {
if (isupper((int)c)) {
*buf++ = 'I';
*buf++ = 'N';
*buf++ = 'F';
} else {
*buf++ = 'i';
*buf++ = 'n';
*buf++ = 'f';
}
} else {
if (isupper((int)c)) {
*buf++ = 'N';
*buf++ = 'A';
*buf++ = 'N';
} else {
*buf++ = 'n';
*buf++ = 'a';
*buf++ = 'n';
}
}
/* No zero-padding with text values */
conv->flag_zero = false;
*bpe = buf;
return bps;
}
/* The case of an F specifier is no longer relevant. */
if (c == 'F') {
c = 'f';
}
/* Handle converting to the hex representation. */
if (IS_ENABLED(CONFIG_CBPRINTF_FP_A_SUPPORT)
&& (IS_ENABLED(CONFIG_CBPRINTF_FP_ALWAYS_A)
|| conv->specifier_a)) {
*buf++ = '0';
*buf++ = 'x';
/* Remove the offset from the exponent, and store the
* non-fractional value. Subnormals require increasing the
* exponent as first bit isn't the implicit bit.
*/
expo -= 1023;
if (is_subnormal) {
*buf++ = '0';
++expo;
} else {
*buf++ = '1';
}
/* If we didn't get precision from a %a specification then we
* treat it as from a %a specification with no precision: full
* range, zero-pruning enabled.
*
* Otherwise we have to cap the precision of the generated
* fraction, or possibly round it.
*/
if (!(conv->specifier_a && conv->prec_present)) {
precision = FRACTION_HEX;
prune_zero = true;
} else if (precision > FRACTION_HEX) {
conv->pad0_pre_exp = precision - FRACTION_HEX;
conv->pad_fp = true;
precision = FRACTION_HEX;
} else if ((fract != 0)
&& (precision < FRACTION_HEX)) {
size_t pos = 4 * (FRACTION_HEX - precision) - 1;
uint64_t mask = BIT64(pos);
/* Round only if the bit that would round is
* set.
*/
if (fract & mask) {
fract += mask;
}
}
/* Record whether we must retain the decimal point even if we
* can prune zeros.
*/
bool require_dp = ((fract != 0) || conv->flag_hash);
if (require_dp || (precision != 0)) {
*buf++ = '.';
}
/* Get the fractional value as a hexadecimal string, using x
* for a and X for A.
*/
struct conversion aconv = {
.specifier = isupper((int)c) ? 'X' : 'x',