Mesa (master): i965: Add functions to convert float <-> VF.
Matt Turner
mattst88 at kemper.freedesktop.org
Wed Nov 26 04:31:59 UTC 2014
Module: Mesa
Branch: master
Commit: c37d798e7829768167626968f3899f72d3e14c55
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=c37d798e7829768167626968f3899f72d3e14c55
Author: Matt Turner <mattst88 at gmail.com>
Date: Thu Apr 3 14:59:26 2014 -0700
i965: Add functions to convert float <-> VF.
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
---
src/mesa/drivers/dri/i965/Makefile.sources | 1 +
src/mesa/drivers/dri/i965/brw_packed_float.c | 75 ++++++++++++++++++++++++++
src/mesa/drivers/dri/i965/brw_reg.h | 4 ++
3 files changed, 80 insertions(+)
diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
index 711aabe..26bf458 100644
--- a/src/mesa/drivers/dri/i965/Makefile.sources
+++ b/src/mesa/drivers/dri/i965/Makefile.sources
@@ -79,6 +79,7 @@ i965_FILES = \
brw_meta_fast_clear.c \
brw_misc_state.c \
brw_object_purgeable.c \
+ brw_packed_float.c \
brw_performance_monitor.c \
brw_program.c \
brw_primitive_restart.c \
diff --git a/src/mesa/drivers/dri/i965/brw_packed_float.c b/src/mesa/drivers/dri/i965/brw_packed_float.c
new file mode 100644
index 0000000..329ba15
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_packed_float.c
@@ -0,0 +1,75 @@
+/*
+ * Copyright © 2014 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+#include "brw_reg.h"
+
+union fu {
+ float f;
+ unsigned u;
+ struct {
+ unsigned mantissa:23;
+ unsigned exponent:8;
+ unsigned sign:1;
+ };
+};
+
+int
+brw_float_to_vf(float f)
+{
+ union fu fu = { .f = f };
+
+ /* ±0.0f is special cased. */
+ if (f == 0.0f)
+ return fu.sign << 7;
+
+ unsigned mantissa = fu.mantissa >> (23 - 4);
+ unsigned exponent = fu.exponent - (127 - 3);
+ unsigned vf = (fu.sign << 7) | (exponent << 4) | mantissa;
+
+ /* 0.125 would have had the same representation as 0.0, so reject it. */
+ if ((vf & 0x7f) == 0)
+ return -1;
+
+ /* Make sure the mantissa fits in 4-bits and the exponent in 3-bits. */
+ if (fu.u & 0x7ffff || exponent > 7)
+ return -1;
+
+ return vf;
+}
+
+float
+brw_vf_to_float(unsigned char vf)
+{
+ union fu fu;
+
+ /* ±0.0f is special cased. */
+ if (vf == 0x00 || vf == 0x80) {
+ fu.u = vf << 24;
+ return fu.f;
+ }
+
+ fu.sign = vf >> 7;
+ fu.exponent = ((vf & 0x70) >> 4) + (127 - 3);
+ fu.mantissa = (vf & 0xf) << (23 - 4);
+
+ return fu.f;
+}
diff --git a/src/mesa/drivers/dri/i965/brw_reg.h b/src/mesa/drivers/dri/i965/brw_reg.h
index 19af0ae..175554b 100644
--- a/src/mesa/drivers/dri/i965/brw_reg.h
+++ b/src/mesa/drivers/dri/i965/brw_reg.h
@@ -881,6 +881,10 @@ brw_indirect(unsigned addr_subnr, int offset)
return ptr;
}
+/* brw_packed_float.c */
+int brw_float_to_vf(float f);
+float brw_vf_to_float(unsigned char vf);
+
#ifdef __cplusplus
}
#endif
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