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panfrost/decode: Decode blend constant

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This adds a forgotten decode line on Midgard and adds the field of a
blend constant on Bifrost. The Bifrost encoding is fairly weird; whereas
Midgard is just a regular 32-bit float, Bifrost uses a fancy
fixed-point-esque encoding. The decode logic here is experimentally
correct. The encode logic is a sort of "guesstimate", assuming that the
high byte is just int(f / 255.0) and then solving algebraicly for the
low byte. This might be slightly off in some cases.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Ryan Houdek <Sonicadvance1@gmail.com>
This commit is contained in:
Alyssa Rosenzweig 2019-05-18 20:48:43 +00:00
parent 3645c781ab
commit ae705387a9
2 changed files with 31 additions and 2 deletions
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16
src/gallium/drivers/panfrost/include/panfrost-job.h
View file

@ -442,7 +442,21 @@ struct bifrost_blend_rt {
/* This is likely an analogue of the flags on
* midgard_blend_rt */
u32 unk1; // = 0x200
u16 flags; // = 0x200
/* Single-channel blend constants are encoded in a sort of
* fixed-point. Basically, the float is mapped to a byte, becoming
* a high byte, and then the lower-byte is added for precision.
* For the original float f:
*
* f = (constant_hi / 255) + (constant_lo / 65535)
*
* constant_hi = int(f / 255)
* constant_lo = 65535*f - (65535/255) * constant_hi
*/
u16 constant;
struct mali_blend_equation equation;
/*
* - 0x19 normally

17
src/gallium/drivers/panfrost/pandecode/decode.c
View file

@ -878,6 +878,17 @@ pandecode_replay_blend_equation(const struct mali_blend_equation *blend)
pandecode_log("},\n");
}
/* Decodes a Bifrost blend constant. See the notes in bifrost_blend_rt */
static unsigned
decode_bifrost_constant(u16 constant)
{
float lo = (float) (constant & 0xFF);
float hi = (float) (constant >> 8);
return (hi / 255.0) + (lo / 65535.0);
}
static mali_ptr
pandecode_bifrost_blend(void *descs, int job_no, int rt_no)
{
@ -887,7 +898,10 @@ pandecode_bifrost_blend(void *descs, int job_no, int rt_no)
pandecode_log("struct bifrost_blend_rt blend_rt_%d_%d = {\n", job_no, rt_no);
pandecode_indent++;
pandecode_prop("unk1 = 0x%" PRIx32, b->unk1);
pandecode_prop("flags = 0x%" PRIx16, b->flags);
pandecode_prop("constant = 0x%" PRIx8 " /* %f */",
b->constant, decode_bifrost_constant(b->constant));
/* TODO figure out blend shader enable bit */
pandecode_replay_blend_equation(&b->equation);
pandecode_prop("unk2 = 0x%" PRIx16, b->unk2);
@ -910,6 +924,7 @@ pandecode_midgard_blend(union midgard_blend *blend, bool is_shader)
pandecode_replay_shader_address("shader", blend->shader);
} else {
pandecode_replay_blend_equation(&blend->equation);
pandecode_prop("constant = %f", blend->constant);
}
pandecode_indent--;