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authorMattias Andrée <maandree@operamail.com>2014-06-04 00:41:31 +0200
committerMattias Andrée <maandree@operamail.com>2014-06-04 00:41:31 +0200
commitd4876331f3c16148f003cf63fb85d9c4298b8bbb (patch)
tree69cafad4269daea832aa87823519188a5c26ba47 /src/lib
parentfix infinite recursion caused by calling wrong function (diff)
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fix float to integer overflow
Signed-off-by: Mattias Andrée <maandree@operamail.com>
Diffstat (limited to '')
-rw-r--r--src/lib/gamma-helper.c164
1 files changed, 153 insertions, 11 deletions
diff --git a/src/lib/gamma-helper.c b/src/lib/gamma-helper.c
index e5f5a25..44e0ff5 100644
--- a/src/lib/gamma-helper.c
+++ b/src/lib/gamma-helper.c
@@ -26,15 +26,156 @@
/**
- * Just an arbitrary version
+ * Just an arbitrary version.
*/
#define ANY bits64
+/**
+ * Concatenation of all ramps.
+ */
+#define ALL red
+
+/**
+ * Preform installation in an `for (i = 0; i < n; i++)`
+ * loop and do a `break` afterwords.
+ */
#define __translate(instruction) for (i = 0; i < n; i++) instruction; break
/**
+ * Convert a [0, 1] `float` to a full range `uint64_t`
+ * and mark sure rounding errors does not cause the
+ * value be 0 instead of ~0 and vice versa.
+ *
+ * @param value To `float` to convert.
+ * @return The value as an `uint64_t`.
+ */
+static inline uint64_t float_to_64(float value)
+{
+ /* XXX Which is faster? */
+
+#ifdef __GNUC__
+ /* `__int128` is a GNU C extension, which
+ (because it is not ISO C) emits a warning
+ under -pedantic. */
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wpedantic"
+
+ /* In GCC we can use `__int128`, this is
+ a signed 128-bit integer. It fits all
+ uint64_t values but also native values,
+ which is a nice because it eleminates
+ some overflow condition tests. It is
+ also more readable. */
+
+ /* Convert to integer. */
+ __int128 product = (__int128)(value * (float)UINT64_MAX);
+ /* Negative overflow. */
+ if (product > UINT64_MAX)
+ return UINT64_MAX;
+ /* Positive overflow. */
+ if (product < 0)
+ return 0;
+ /* Did not overflow. */
+ return (uint64_t)product;
+
+# pragma GCC diagnostic pop
+#else
+
+ /* If we are not using GCC we cannot be
+ sure that we have `__int128` so we have
+ to use `uint64_t` and perform overflow
+ checkes based on the input value. */
+
+ /* Convert to integer. */
+ uint64_t product = (uint64_t)(value * (float)UINT64_MAX);
+ /* Negative overflow,
+ if the input is less than 0,5 but
+ the output is greater then we got
+ -1 when we should have gotten 0. */
+ if ((value < 0.1f) && (product > 0xF000000000000000ULL))
+ return 0;
+ /* Positive overflow,
+ if the input is greater than 0,5
+ but the output is less then we got
+ 0 when we should have gotten ~0. */
+ else if ((value > 0.9f) && (product < 0x1000000000000000ULL))
+ return (uint64_t)~0;
+ /* Did not overflow. */
+ return product;
+
+#endif
+}
+
+
+/**
+ * Convert a [0, 1] `double` to a full range `uint64_t`
+ * and mark sure rounding errors does not cause the
+ * value be 0 instead of ~0 and vice versa.
+ *
+ * @param value To `double` to convert.
+ * @return The value as an `uint64_t`.
+ */
+static inline uint64_t double_to_64(double value)
+{
+ /* XXX Which is faster? */
+
+#ifdef __GNUC__
+ /* `__int128` is a GNU C extension, which
+ (because it is not ISO C) emits a warning
+ under -pedantic. */
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wpedantic"
+
+ /* In GCC we can use `__int128`, this is
+ a signed 128-bit integer. It fits all
+ uint64_t values but also native values,
+ which is a nice because it eleminates
+ some overflow condition tests. It is
+ also more readable. */
+
+ /* Convert to integer. */
+ __int128 product = (__int128)(value * (double)UINT64_MAX);
+ /* Negative overflow. */
+ if (product > UINT64_MAX)
+ return UINT64_MAX;
+ /* Positive overflow. */
+ if (product < 0)
+ return 0;
+ /* Did not overflow. */
+ return (uint64_t)product;
+
+# pragma GCC diagnostic pop
+#else
+
+ /* If we are not using GCC we cannot be
+ sure that we have `__int128` so we have
+ to use `uint64_t` and perform overflow
+ checkes based on the input value. */
+
+ /* Convert to integer. */
+ uint64_t product = (uint64_t)(value * (double)UINT64_MAX);
+ /* Negative overflow,
+ if the input is less than 0,5 but
+ the output is greater then we got
+ -1 when we should have gotten 0. */
+ if ((value < (double)0.1f) && (product > 0xF000000000000000ULL))
+ product = 0;
+ /* Positive overflow.
+ if the input is greater than 0,5
+ but the output is less then we got
+ 0 when we should have gotten ~0. */
+ else if ((value > (double)0.9f) && (product < 0x1000000000000000ULL))
+ product = (uint64_t)~0;
+ /* Did not overflow. */
+ return product;
+
+#endif
+}
+
+
+/**
* Convert any set of gamma ramps into a 64-bit integer array with all channels.
*
* @param depth The depth of the gamma ramp, `-1` for `float`, `-2` for `double`.
@@ -48,13 +189,13 @@ static void translate_to_64(signed depth, size_t n, uint64_t* restrict out, libg
switch (depth)
{
/* Translate integer. */
- case 16: __translate(out[i] = (uint64_t)(in.bits16.red[i]) * 0x0001000100010001ULL);
- case 32: __translate(out[i] = (uint64_t)(in.bits32.red[i]) * 0x0000000100000001ULL);
+ case 16: __translate(out[i] = (uint64_t)(in.bits16.ALL[i]) * 0x0001000100010001ULL);
+ case 32: __translate(out[i] = (uint64_t)(in.bits32.ALL[i]) * 0x0000000100000001ULL);
/* Identity translation. */
- case 64: __translate(out[i] = in.bits64.red[i]);
+ case 64: __translate(out[i] = in.bits64.ALL[i]);
/* Translate floating point. */
- case -1: __translate(out[i] = (uint64_t)(in.float_single.red[i] * (float)UINT64_MAX));
- case -2: __translate(out[i] = (uint64_t)(in.float_double.red[i] * (double)UINT64_MAX));
+ case -1: __translate(out[i] = float_to_64(in.float_single.ALL[i]));
+ case -2: __translate(out[i] = double_to_64(in.float_double.ALL[i]));
default:
/* This is not possible. */
abort();
@@ -77,13 +218,13 @@ static void translate_from_64(signed depth, size_t n, libgamma_gamma_ramps_any_t
switch (depth)
{
/* Translate integer. */
- case 16: __translate(out.bits16.red[i] = (uint16_t)(in[i] / 0x0001000100010001ULL));
- case 32: __translate(out.bits32.red[i] = (uint32_t)(in[i] / 0x0000000100000001ULL));
+ case 16: __translate(out.bits16.ALL[i] = (uint16_t)(in[i] / 0x0001000100010001ULL));
+ case 32: __translate(out.bits32.ALL[i] = (uint32_t)(in[i] / 0x0000000100000001ULL));
/* Identity translation. */
- case 64: __translate(out.bits64.red[i] = in[i]);
+ case 64: __translate(out.bits64.ALL[i] = in[i]);
/* Translate floating point. */
- case -1: __translate(out.float_single.red[i] = (float)(in[i]) / (float)UINT64_MAX);
- case -2: __translate(out.float_double.red[i] = (double)(in[i]) / (double)UINT64_MAX);
+ case -1: __translate(out.float_single.ALL[i] = (float)(in[i]) / (float)UINT64_MAX);
+ case -2: __translate(out.float_double.ALL[i] = (double)(in[i]) / (double)UINT64_MAX);
default:
/* This is not possible. */
abort();
@@ -229,5 +370,6 @@ int libgamma_translated_ramp_set_(libgamma_crtc_state_t* restrict this,
#undef __translate
+#undef ALL
#undef ANY