/* tarith.c
*
* Copyright (c) 2011-2013 John Cunningham Bowler
*
* Last changed in libpng 1.6.0 [February 14, 2013]
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
* Test internal arithmetic functions of libpng.
*
* This code must be linked against a math library (-lm), but does not require
* libpng or zlib to work. Because it includes the complete source of 'png.c'
* it tests the code with whatever compiler options are used to build it.
* Changing these options can substantially change the errors in the
* calculations that the compiler chooses!
*/
#define _POSIX_SOURCE 1
#define _ISOC99_SOURCE 1
/* Obtain a copy of the code to be tested (plus other things), disabling
* stuff that is not required.
*/
#include <math.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <assert.h>
#include "../../pngpriv.h"
#define png_error png_warning
void png_warning(png_const_structrp png_ptr, png_const_charp msg)
{
fprintf(stderr, "validation: %s\n", msg);
}
#define png_fixed_error png_fixed_warning
void png_fixed_warning(png_const_structrp png_ptr, png_const_charp msg)
{
fprintf(stderr, "overflow in: %s\n", msg);
}
#define png_set_error_fn(pp, ep, efp, wfp) ((void)0)
#define png_malloc(pp, s) malloc(s)
#define png_malloc_warn(pp, s) malloc(s)
#define png_malloc_base(pp, s) malloc(s)
#define png_calloc(pp, s) calloc(1, (s))
#define png_free(pp, s) free(s)
#define png_safecat(b, sb, pos, str) (pos)
#define png_format_number(start, end, format, number) (start)
#define crc32(crc, pp, s) (crc)
#define inflateReset(zs) Z_OK
#define png_create_struct(type) (0)
#define png_destroy_struct(pp) ((void)0)
#define png_create_struct_2(type, m, mm) (0)
#define png_destroy_struct_2(pp, f, mm) ((void)0)
#undef PNG_SIMPLIFIED_READ_SUPPORTED
#undef PNG_SIMPLIFIED_WRITE_SUPPORTED
#undef PNG_USER_MEM_SUPPORTED
#include "../../png.c"
/* Validate ASCII to fp routines. */
static int verbose = 0;
int validation_ascii_to_fp(int count, int argc, char **argv)
{
int showall = 0;
double max_error=2; /* As a percentage error-in-last-digit/.5 */
double max_error_abs=17; /* Used when precision is DBL_DIG */
double max = 0;
double max_abs = 0;
double test = 0; /* Important to test this. */
int precision = 5;
int nonfinite = 0;
int finite = 0;
int ok = 0;
int failcount = 0;
int minorarith = 0;
while (--argc > 0)
if (strcmp(*++argv, "-a") == 0)
showall = 1;
else if (strcmp(*argv, "-e") == 0 && argc > 0)
{
--argc;
max_error = atof(*++argv);
}
else if (strcmp(*argv, "-E") == 0 && argc > 0)
{
--argc;
max_error_abs = atof(*++argv);
}
else
{
fprintf(stderr, "unknown argument %s\n", *argv);
return 1;
}
do
{
png_size_t index;
int state, failed = 0;
char buffer[64];
if (isfinite(test))
++finite;
else
++nonfinite;
if (verbose)
fprintf(stderr, "%.*g %d\n", DBL_DIG, test, precision);
/* Check for overflow in the buffer by setting a marker. */
memset(buffer, 71, sizeof buffer);
png_ascii_from_fp(0, buffer, precision+10, test, precision);
/* Allow for a three digit exponent, this stuff will fail if
* the exponent is bigger than this!
*/
if (buffer[precision+7] != 71)
{
fprintf(stderr, "%g[%d] -> '%s'[%lu] buffer overflow\n", test,
precision, buffer, (unsigned long)strlen(buffer));
failed = 1;
}
/* Following are used for the number parser below and must be
* initialized to zero.
*/
state = 0;
index = 0;
if (!isfinite(test))
{
/* Expect 'inf' */
if (test >= 0 && strcmp(buffer, "inf") ||
test < 0 && strcmp(buffer, "-inf"))
{
fprintf(stderr, "%g[%d] -> '%s' but expected 'inf'\n", test,
precision, buffer);
failed = 1;
}
}
else if (!png_check_fp_number(buffer, precision+10, &state, &index) ||
buffer[index] != 0)
{
fprintf(stderr, "%g[%d] -> '%s' but has bad format ('%c')\n", test,
precision, buffer, buffer[index]);
failed = 1;
}
else if (PNG_FP_IS_NEGATIVE(state) && !(test < 0))
{
fprintf(stderr, "%g[%d] -> '%s' but negative value not so reported\n",
test, precision, buffer);
failed = 1;
assert(!PNG_FP_IS_ZERO(state));
assert(!PNG_FP_IS_POSITIVE(state));
}
else if (PNG_FP_IS_ZERO(state) && !(test == 0))
{
fprintf(stderr, "%g[%d] -> '%s' but zero value not so reported\n",
test, precision, buffer);
failed = 1;
assert(!PNG_FP_IS_NEGATIVE(state));
assert(!PNG_FP_IS_POSITIVE(state));
}
else if (PNG_FP_IS_POSITIVE(state) && !(test > 0))
{
fprintf(stderr, "%g[%d] -> '%s' but postive value not so reported\n",
test, precision, buffer);
failed = 1;
assert(!PNG_FP_IS_NEGATIVE(state));
assert(!PNG_FP_IS_ZERO(state));
}
else
{
/* Check the result against the original. */
double out = atof(buffer);
double change = fabs((out - test)/test);
double allow = .5/pow(10,
(precision >= DBL_DIG) ? DBL_DIG-1 : precision-1);
/* NOTE: if you hit this error case are you compiling with gcc
* and -O0? Try -O2 - the errors can accumulate if the FP
* code above is not optimized and may drift outside the .5 in
* DBL_DIG allowed. In any case a small number of errors may
* occur (very small ones - 1 or 2%) because of rounding in the
* calculations, either in the conversion API or in atof.
*/
if (change >= allow && (isfinite(out) ||
fabs(test/DBL_MAX) <= 1-allow))
{
double percent = (precision >= DBL_DIG) ? max_error_abs : max_error;
double allowp = (change-allow)*100/allow;
if (precision >= DBL_DIG)
{
if (max_abs < allowp) max_abs = allowp;
}
else
{
if (max < allowp) max = allowp;
}
if (showall || allowp >= percent)
{
fprintf(stderr,
"%.*g[%d] -> '%s' -> %.*g number changed (%g > %g (%d%%))\n",
DBL_DIG, test, precision, buffer, DBL_DIG, out, change, allow,
(int)round(allowp));
failed = 1;
}
else
++minorarith;
}
}
if (failed)
++failcount;
else
++ok;
skip:
/* Generate a new number and precision. */
precision = rand();
if (precision & 1) test = -test;
precision >>= 1;
/* Generate random numbers. */
if (test == 0 || !isfinite(test))
test = precision+1;
else
{
/* Derive the exponent from the previous rand() value. */
int exponent = precision % (DBL_MAX_EXP - DBL_MIN_EXP) + DBL_MIN_EXP;
int tmp;
test = frexp(test * rand(), &tmp);
test = ldexp(test, exponent);
precision >>= 8; /* arbitrary */
}
/* This limits the precision to 32 digits, enough for standard
* IEEE implementations which have at most 15 digits.
*/
precision = (precision & 0x1f) + 1;
}
while (--count);
printf("Tested %d finite values, %d non-finite, %d OK (%d failed) %d minor "
"arithmetic errors\n", finite, nonfinite, ok, failcount, minorarith);
printf(" Error with >=%d digit precision %.2f%%\n", DBL_DIG, max_abs);
printf(" Error with < %d digit precision %.2f%%\n", DBL_DIG, max);
return 0;
}
/* Observe that valid FP numbers have the forms listed in the PNG extensions
* specification:
*
* [+,-]{integer,integer.fraction,.fraction}[{e,E}[+,-]integer]
*
* Test each of these in turn, including invalid cases.
*/
typedef enum checkfp_state
{
start, fraction, exponent, states
} checkfp_state;
/* The characters (other than digits) that characterize the states: */
static const char none[] = "";
static const char hexdigits[16] = "0123456789ABCDEF";
static const struct
{
const char *start; /* Characters valid at the start */
const char *end; /* Valid characters that end the state */
const char *tests; /* Characters to test after 2 digits seen */
}
state_characters[states] =
{
/* start: */ { "+-.", ".eE", "+-.e*0369" },
/* fraction: */ { none, "eE", "+-.E#0147" },
/* exponent: */ { "+-", none, "+-.eE^0258" }
};
typedef struct
{
char number[1024]; /* Buffer for number being tested */
int limit; /* Command line limit */
int verbose; /* Shadows global variable */
int ctimes; /* Number of numbers tested */
int cmillions; /* Count of millions of numbers */
int cinvalid; /* Invalid strings checked */
int cnoaccept; /* Characters not accepted */
}
checkfp_command;
typedef struct
{
int cnumber; /* Index into number string */
checkfp_state check_state; /* Current number state */
int at_start; /* At start (first character) of state */
int cdigits_in_state; /* Digits seen in that state */
int limit; /* Limit on same for checking all chars */
int state; /* Current parser state */
int is_negative; /* Number is negative */
int is_zero; /* Number is (still) zero */
int number_was_valid; /* Previous character validity */
}
checkfp_control;
static int check_all_characters(checkfp_command *co, checkfp_control c);
static int check_some_characters(checkfp_command *co, checkfp_control c,
const char *tests);
static int check_one_character(checkfp_command *co, checkfp_control c, int ch)
{
/* Test this character (ch) to ensure the parser does the correct thing.
*/
png_size_t index = 0;
const char test = (char)ch;
const int number_is_valid = png_check_fp_number(&test, 1, &c.state, &index);
const int character_accepted = (index == 1);
if (c.check_state != exponent && isdigit(ch) && ch != '0')
c.is_zero = 0;
if (c.check_state == start && c.at_start && ch == '-')
c.is_negative = 1;
if (isprint(ch))
co->number[c.cnumber++] = (char)ch;
else
{
co->number[c.cnumber++] = '<';
co->number[c.cnumber++] = hexdigits[(ch >> 4) & 0xf];
co->number[c.cnumber++] = hexdigits[ch & 0xf];
co->number[c.cnumber++] = '>';
}
co->number[c.cnumber] = 0;
if (co->verbose > 1)
fprintf(stderr, "%s\n", co->number);
if (++(co->ctimes) == 1000000)
{
if (co->verbose == 1)
fputc('.', stderr);
co->ctimes = 0;
++(co->cmillions);
}
if (!number_is_valid)
++(co->cinvalid);
if (!character_accepted)
++(co->cnoaccept);
/* This should never fail (it's a serious bug if it does): */
if (index != 0 && index != 1)
{
fprintf(stderr, "%s: read beyond end of string (%lu)\n", co->number,
(unsigned long)index);
return 0;
}
/* Validate the new state, note that the PNG_FP_IS_ macros all return
* false unless the number is valid.
*/
if (PNG_FP_IS_NEGATIVE(c.state) !=
(number_is_valid && !c.is_zero && c.is_negative))
{
fprintf(stderr, "%s: negative when it is not\n", co->number);
return 0;
}
if (PNG_FP_IS_ZERO(c.state) != (number_is_valid && c.is_zero))
{
fprintf(stderr, "%s: zero when it is not\n", co->number);
return 0;
}
if (PNG_FP_IS_POSITIVE(c.state) !=
(number_is_valid && !c.is_zero && !c.is_negative))
{
fprintf(stderr, "%s: positive when it is not\n", co->number);
return 0;
}
/* Testing a digit */
if (isdigit(ch))
{
if (!character_accepted)
{
fprintf(stderr, "%s: digit '%c' not accepted\n", co->number, ch);
return 0;
}
if (!number_is_valid)
{
fprintf(stderr, "%s: saw a digit (%c) but number not valid\n",
co->number, ch);
return 0;
}
++c.cdigits_in_state;
c.at_start = 0;
c.number_was_valid = 1;
/* Continue testing characters in this state. Either test all of
* them or, if we have already seen one digit in this state, just test a
* limited set.
*/
if (c.cdigits_in_state < 1)
return check_all_characters(co, c);
else
return check_some_characters(co, c,
state_characters[c.check_state].tests);
}
/* A non-digit; is it allowed here? */
else if (((ch == '+' || ch == '-') && c.check_state != fraction &&
c.at_start) ||
(ch == '.' && c.check_state == start) ||
((ch == 'e' || ch == 'E') && c.number_was_valid &&
c.check_state != exponent))
{
if (!character_accepted)
{
fprintf(stderr, "%s: character '%c' not accepted\n", co->number, ch);
return 0;
}
/* The number remains valid after start of fraction but nowhere else. */
if (number_is_valid && (c.check_state != start || ch != '.'))
{
fprintf(stderr, "%s: saw a non-digit (%c) but number valid\n",
co->number, ch);
return 0;
}
c.number_was_valid = number_is_valid;
/* Check for a state change. When changing to 'fraction' if the number
* is valid at this point set the at_start to false to allow an exponent
* 'e' to come next.
*/
if (c.check_state == start && ch == '.')
{
c.check_state = fraction;
c.at_start = !number_is_valid;
c.cdigits_in_state = 0;
c.limit = co->limit;
return check_all_characters(co, c);
}
else if (c.check_state < exponent && (ch == 'e' || ch == 'E'))
{
c.check_state = exponent;
c.at_start = 1;
c.cdigits_in_state = 0;
c.limit = co->limit;
return check_all_characters(co, c);
}
/* Else it was a sign, and the state doesn't change. */
else
{
if (ch != '-' && ch != '+')
{
fprintf(stderr, "checkfp: internal error (1)\n");
return 0;
}
c.at_start = 0;
return check_all_characters(co, c);
}
}
/* Testing an invalid character */
else
{
if (character_accepted)
{
fprintf(stderr, "%s: character '%c' [0x%.2x] accepted\n", co->number,
ch, ch);
return 0;
}
if (number_is_valid != c.number_was_valid)
{
fprintf(stderr,
"%s: character '%c' [0x%.2x] changed number validity\n", co->number,
ch, ch);
return 0;
}
/* Do nothing - the parser has stuck; return success and keep going with
* the next character.
*/
}
/* Successful return (the caller will try the next character.) */
return 1;
}
static int check_all_characters(checkfp_command *co, checkfp_control c)
{
int ch;
if (c.cnumber+4 < sizeof co->number) for (ch=0; ch<256; ++ch)
{
if (!check_one_character(co, c, ch))
return 0;
}
return 1;
}
static int check_some_characters(checkfp_command *co, checkfp_control c,
const char *tests)
{
int i;
--(c.limit);
if (c.cnumber+4 < sizeof co->number && c.limit >= 0)
{
if (c.limit > 0) for (i=0; tests[i]; ++i)
{
if (!check_one_character(co, c, tests[i]))
return 0;
}
/* At the end check all the characters. */
else
return check_all_characters(co, c);
}
return 1;
}
int validation_checkfp(int count, int argc, char **argv)
{
int result;
checkfp_command command;
checkfp_control control;
command.number[0] = 0;
command.limit = 3;
command.verbose = verbose;
command.ctimes = 0;
command.cmillions = 0;
command.cinvalid = 0;
command.cnoaccept = 0;
while (--argc > 0)
{
++argv;
if (argc > 1 && strcmp(*argv, "-l") == 0)
{
--argc;
command.limit = atoi(*++argv);
}
else
{
fprintf(stderr, "unknown argument %s\n", *argv);
return 1;
}
}
control.cnumber = 0;
control.check_state = start;
control.at_start = 1;
control.cdigits_in_state = 0;
control.limit = command.limit;
control.state = 0;
control.is_negative = 0;
control.is_zero = 1;
control.number_was_valid = 0;
result = check_all_characters(&command, control);
printf("checkfp: %s: checked %d,%.3d,%.3d,%.3d strings (%d invalid)\n",
result ? "pass" : "FAIL", command.cmillions / 1000,
command.cmillions % 1000, command.ctimes / 1000, command.ctimes % 1000,
command.cinvalid);
return result;
}
int validation_muldiv(int count, int argc, char **argv)
{
int tested = 0;
int overflow = 0;
int error = 0;
int error64 = 0;
int passed = 0;
int randbits = 0;
png_uint_32 randbuffer;
png_fixed_point a;
png_int_32 times, div;
while (--argc > 0)
{
fprintf(stderr, "unknown argument %s\n", *++argv);
return 1;
}
/* Find out about the random number generator. */
randbuffer = RAND_MAX;
while (randbuffer != 0) ++randbits, randbuffer >>= 1;
printf("Using random number generator that makes %d bits\n", randbits);
for (div=0; div<32; div += randbits)
randbuffer = (randbuffer << randbits) ^ rand();
a = 0;
times = div = 0;
do
{
png_fixed_point result;
/* NOTE: your mileage may vary, a type is required below that can
* hold 64 bits or more, if floating point is used a 64 bit or
* better mantissa is required.
*/
long long int fp, fpround;
unsigned long hi, lo;
int ok;
/* Check the values, png_64bit_product can only handle positive
* numbers, so correct for that here.
*/
{
long u1, u2;
int n = 0;
if (a < 0) u1 = -a, n = 1; else u1 = a;
if (times < 0) u2 = -times, n = !n; else u2 = times;
png_64bit_product(u1, u2, &hi, &lo);
if (n)
{
/* -x = ~x+1 */
lo = ((~lo) + 1) & 0xffffffff;
hi = ~hi;
if (lo == 0) ++hi;
}
}
fp = a;
fp *= times;
if ((fp & 0xffffffff) != lo || ((fp >> 32) & 0xffffffff) != hi)
{
fprintf(stderr, "png_64bit_product %d * %d -> %lx|%.8lx not %llx\n",
a, times, hi, lo, fp);
++error64;
}
if (div != 0)
{
/* Round - this is C round to zero. */
if ((fp < 0) != (div < 0))
fp -= div/2;
else
fp += div/2;
fp /= div;
fpround = fp;
/* Assume 2's complement here: */
ok = fpround <= PNG_UINT_31_MAX &&
fpround >= -1-(long long int)PNG_UINT_31_MAX;
if (!ok) ++overflow;
}
else
ok = 0, ++overflow, fpround = fp/*misleading*/;
if (verbose)
fprintf(stderr, "TEST %d * %d / %d -> %lld (%s)\n", a, times, div,
fp, ok ? "ok" : "overflow");
++tested;
if (png_muldiv(&result, a, times, div) != ok)
{
++error;
if (ok)
fprintf(stderr, "%d * %d / %d -> overflow (expected %lld)\n", a,
times, div, fp);
else
fprintf(stderr, "%d * %d / %d -> %d (expected overflow %lld)\n", a,
times, div, result, fp);
}
else if (ok && result != fpround)
{
++error;
fprintf(stderr, "%d * %d / %d -> %d not %lld\n", a, times, div, result,
fp);
}
else
++passed;
/* Generate three new values, this uses rand() and rand() only returns
* up to RAND_MAX.
*/
/* CRUDE */
a += times;
times += div;
div = randbuffer;
randbuffer = (randbuffer << randbits) ^ rand();
}
while (--count > 0);
printf("%d tests including %d overflows, %d passed, %d failed (%d 64 bit "
"errors)\n", tested, overflow, passed, error, error64);
return 0;
}
/* When FP is on this just becomes a speed test - compile without FP to get real
* validation.
*/
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
#define LN2 .000010576586617430806112933839 /* log(2)/65536 */
#define L2INV 94548.46219969910586572651 /* 65536/log(2) */
/* For speed testing, need the internal functions too: */
static png_uint_32 png_log8bit(unsigned x)
{
if (x > 0)
return (png_uint_32)floor(.5-log(x/255.)*L2INV);
return 0xffffffff;
}
static png_uint_32 png_log16bit(png_uint_32 x)
{
if (x > 0)
return (png_uint_32)floor(.5-log(x/65535.)*L2INV);
return 0xffffffff;
}
static png_uint_32 png_exp(png_uint_32 x)
{
return (png_uint_32)floor(.5 + exp(x * -LN2) * 0xffffffffU);
}
static png_byte png_exp8bit(png_uint_32 log)
{
return (png_byte)floor(.5 + exp(log * -LN2) * 255);
}
static png_uint_16 png_exp16bit(png_uint_32 log)
{
return (png_uint_16)floor(.5 + exp(log * -LN2) * 65535);
}
#endif /* FLOATING_ARITHMETIC */
int validation_gamma(int argc, char **argv)
{
double gamma[9] = { 2.2, 1.8, 1.52, 1.45, 1., 1/1.45, 1/1.52, 1/1.8, 1/2.2 };
double maxerr;
int i, silent=0, onlygamma=0;
/* Silence the output with -s, just test the gamma functions with -g: */
while (--argc > 0)
if (strcmp(*++argv, "-s") == 0)
silent = 1;
else if (strcmp(*argv, "-g") == 0)
onlygamma = 1;
else
{
fprintf(stderr, "unknown argument %s\n", *argv);
return 1;
}
if (!onlygamma)
{
/* First validate the log functions: */
maxerr = 0;
for (i=0; i<256; ++i)
{
double correct = -log(i/255.)/log(2.)*65536;
double error = png_log8bit(i) - correct;
if (i != 0 && fabs(error) > maxerr)
maxerr = fabs(error);
if (i == 0 && png_log8bit(i) != 0xffffffff ||
i != 0 && png_log8bit(i) != floor(correct+.5))
{
fprintf(stderr, "8 bit log error: %d: got %u, expected %f\n",
i, png_log8bit(i), correct);
}
}
if (!silent)
printf("maximum 8 bit log error = %f\n", maxerr);
maxerr = 0;
for (i=0; i<65536; ++i)
{
double correct = -log(i/65535.)/log(2.)*65536;
double error = png_log16bit(i) - correct;
if (i != 0 && fabs(error) > maxerr)
maxerr = fabs(error);
if (i == 0 && png_log16bit(i) != 0xffffffff ||
i != 0 && png_log16bit(i) != floor(correct+.5))
{
if (error > .68) /* By experiment error is less than .68 */
{
fprintf(stderr, "16 bit log error: %d: got %u, expected %f"
" error: %f\n", i, png_log16bit(i), correct, error);
}
}
}
if (!silent)
printf("maximum 16 bit log error = %f\n", maxerr);
/* Now exponentiations. */
maxerr = 0;
for (i=0; i<=0xfffff; ++i)
{
double correct = exp(-i/65536. * log(2.)) * (65536. * 65536);
double error = png_exp(i) - correct;
if (fabs(error) > maxerr)
maxerr = fabs(error);
if (fabs(error) > 1883) /* By experiment. */
{
fprintf(stderr, "32 bit exp error: %d: got %u, expected %f"
" error: %f\n", i, png_exp(i), correct, error);
}
}
if (!silent)
printf("maximum 32 bit exp error = %f\n", maxerr);
maxerr = 0;
for (i=0; i<=0xfffff; ++i)
{
double correct = exp(-i/65536. * log(2.)) * 255;
double error = png_exp8bit(i) - correct;
if (fabs(error) > maxerr)
maxerr = fabs(error);
if (fabs(error) > .50002) /* By experiment */
{
fprintf(stderr, "8 bit exp error: %d: got %u, expected %f"
" error: %f\n", i, png_exp8bit(i), correct, error);
}
}
if (!silent)
printf("maximum 8 bit exp error = %f\n", maxerr);
maxerr = 0;
for (i=0; i<=0xfffff; ++i)
{
double correct = exp(-i/65536. * log(2.)) * 65535;
double error = png_exp16bit(i) - correct;
if (fabs(error) > maxerr)
maxerr = fabs(error);
if (fabs(error) > .524) /* By experiment */
{
fprintf(stderr, "16 bit exp error: %d: got %u, expected %f"
" error: %f\n", i, png_exp16bit(i), correct, error);
}
}
if (!silent)
printf("maximum 16 bit exp error = %f\n", maxerr);
} /* !onlygamma */
/* Test the overall gamma correction. */
for (i=0; i<9; ++i)
{
unsigned j;
double g = gamma[i];
png_fixed_point gfp = floor(g * PNG_FP_1 + .5);
if (!silent)
printf("Test gamma %f\n", g);
maxerr = 0;
for (j=0; j<256; ++j)
{
double correct = pow(j/255., g) * 255;
png_byte out = png_gamma_8bit_correct(j, gfp);
double error = out - correct;
if (fabs(error) > maxerr)
maxerr = fabs(error);
if (out != floor(correct+.5))
{
fprintf(stderr, "8bit %d ^ %f: got %d expected %f error %f\n",
j, g, out, correct, error);
}
}
if (!silent)
printf("gamma %f: maximum 8 bit error %f\n", g, maxerr);
maxerr = 0;
for (j=0; j<65536; ++j)
{
double correct = pow(j/65535., g) * 65535;
png_uint_16 out = png_gamma_16bit_correct(j, gfp);
double error = out - correct;
if (fabs(error) > maxerr)
maxerr = fabs(error);
if (fabs(error) > 1.62)
{
fprintf(stderr, "16bit %d ^ %f: got %d expected %f error %f\n",
j, g, out, correct, error);
}
}
if (!silent)
printf("gamma %f: maximum 16 bit error %f\n", g, maxerr);
}
return 0;
}
/**************************** VALIDATION TESTS ********************************/
/* Various validation routines are included herein, they require some
* definition for png_warning and png_error, seetings of VALIDATION:
*
* 1: validates the ASCII to floating point conversions
* 2: validates png_muldiv
* 3: accuracy test of fixed point gamma tables
*/
/* The following COUNT (10^8) takes about 1 hour on a 1GHz Pentium IV
* processor.
*/
#define COUNT 1000000000
int main(int argc, char **argv)
{
int count = COUNT;
while (argc > 1)
{
if (argc > 2 && strcmp(argv[1], "-c") == 0)
{
count = atoi(argv[2]);
argc -= 2;
argv += 2;
}
else if (strcmp(argv[1], "-v") == 0)
{
++verbose;
--argc;
++argv;
}
else
break;
}
if (count > 0 && argc > 1)
{
if (strcmp(argv[1], "ascii") == 0)
return validation_ascii_to_fp(count, argc-1, argv+1);
else if (strcmp(argv[1], "checkfp") == 0)
return validation_checkfp(count, argc-1, argv+1);
else if (strcmp(argv[1], "muldiv") == 0)
return validation_muldiv(count, argc-1, argv+1);
else if (strcmp(argv[1], "gamma") == 0)
return validation_gamma(argc-1, argv+1);
}
/* Bad argument: */
fprintf(stderr,
"usage: tarith [-v] [-c count] {ascii,muldiv,gamma} [args]\n");
fprintf(stderr, " arguments: ascii [-a (all results)] [-e error%%]\n");
fprintf(stderr, " checkfp [-l max-number-chars]\n");
fprintf(stderr, " muldiv\n");
fprintf(stderr, " gamma -s (silent) -g (only gamma; no log)\n");
return 1;
}