/**
* Extract Y, U, V channels from packed YUYV.
* @param packed is a <n x i32> vector with the packed YUYV blocks
* @param i is a <n x i32> vector with the x pixel coordinate (0 or 1)
*/
static void
yuyv_to_yuv_soa(struct gallivm_state *gallivm,
unsigned n,
LLVMValueRef packed,
LLVMValueRef i,
LLVMValueRef *y,
LLVMValueRef *u,
LLVMValueRef *v)
{
LLVMBuilderRef builder = gallivm->builder;
struct lp_type type;
LLVMValueRef mask;
memset(&type, 0, sizeof type);
type.width = 32;
type.length = n;
assert(lp_check_value(type, packed));
assert(lp_check_value(type, i));
/*
* y = (yuyv >> 16*i) & 0xff
* u = (yuyv >> 8 ) & 0xff
* v = (yuyv >> 24 ) & 0xff
*/
#if defined(PIPE_ARCH_X86) || defined(PIPE_ARCH_X86_64)
/*
* Avoid shift with per-element count.
* No support on x86, gets translated to roughly 5 instructions
* per element. Didn't measure performance but cuts shader size
* by quite a bit (less difference if cpu has no sse4.1 support).
*/
if (util_cpu_caps.has_sse2 && n == 4) {
LLVMValueRef sel, tmp;
struct lp_build_context bld32;
lp_build_context_init(&bld32, gallivm, type);
tmp = LLVMBuildLShr(builder, packed, lp_build_const_int_vec(gallivm, type, 16), "");
sel = lp_build_compare(gallivm, type, PIPE_FUNC_EQUAL, i, lp_build_const_int_vec(gallivm, type, 0));
*y = lp_build_select(&bld32, sel, packed, tmp);
} else
#endif
{
LLVMValueRef shift;
shift = LLVMBuildMul(builder, i, lp_build_const_int_vec(gallivm, type, 16), "");
*y = LLVMBuildLShr(builder, packed, shift, "");
}
*u = LLVMBuildLShr(builder, packed, lp_build_const_int_vec(gallivm, type, 8), "");
*v = LLVMBuildLShr(builder, packed, lp_build_const_int_vec(gallivm, type, 24), "");
mask = lp_build_const_int_vec(gallivm, type, 0xff);
*y = LLVMBuildAnd(builder, *y, mask, "y");
*u = LLVMBuildAnd(builder, *u, mask, "u");
*v = LLVMBuildAnd(builder, *v, mask, "v");
}
/**
* Build code to compare two values 'a' and 'b' using the given func.
* \param func one of PIPE_FUNC_x
* The result values will be 0 for false or ~0 for true.
*/
LLVMValueRef
lp_build_cmp(struct lp_build_context *bld,
unsigned func,
LLVMValueRef a,
LLVMValueRef b)
{
return lp_build_compare(bld->gallivm, bld->type, func, a, b);
}
static LLVMValueRef
generate_scissor_test(LLVMBuilderRef builder,
LLVMValueRef context_ptr,
const struct lp_build_interp_soa_context *interp,
struct lp_type type)
{
LLVMTypeRef vec_type = lp_build_vec_type(type);
LLVMValueRef xpos = interp->pos[0], ypos = interp->pos[1];
LLVMValueRef xmin, ymin, xmax, ymax;
LLVMValueRef m0, m1, m2, m3, m;
/* xpos, ypos contain the window coords for the four pixels in the quad */
assert(xpos);
assert(ypos);
/* get the current scissor bounds, convert to vectors */
xmin = lp_jit_context_scissor_xmin_value(builder, context_ptr);
xmin = lp_build_broadcast(builder, vec_type, xmin);
ymin = lp_jit_context_scissor_ymin_value(builder, context_ptr);
ymin = lp_build_broadcast(builder, vec_type, ymin);
xmax = lp_jit_context_scissor_xmax_value(builder, context_ptr);
xmax = lp_build_broadcast(builder, vec_type, xmax);
ymax = lp_jit_context_scissor_ymax_value(builder, context_ptr);
ymax = lp_build_broadcast(builder, vec_type, ymax);
/* compare the fragment's position coordinates against the scissor bounds */
m0 = lp_build_compare(builder, type, PIPE_FUNC_GEQUAL, xpos, xmin);
m1 = lp_build_compare(builder, type, PIPE_FUNC_GEQUAL, ypos, ymin);
m2 = lp_build_compare(builder, type, PIPE_FUNC_LESS, xpos, xmax);
m3 = lp_build_compare(builder, type, PIPE_FUNC_LESS, ypos, ymax);
/* AND all the masks together */
m = LLVMBuildAnd(builder, m0, m1, "");
m = LLVMBuildAnd(builder, m, m2, "");
m = LLVMBuildAnd(builder, m, m3, "");
lp_build_name(m, "scissormask");
return m;
}
/**
* Convert srgb int values to linear float values.
* Several possibilities how to do this, e.g.
* - table
* - doing the pow() with int-to-float and float-to-int tricks
* (http://stackoverflow.com/questions/6475373/optimizations-for-pow-with-const-non-integer-exponent)
* - just using standard polynomial approximation
* (3rd order polynomial is required for crappy but just sufficient accuracy)
*
* @param src integer (vector) value(s) to convert
* (chan_bits bit values unpacked to 32 bit already).
*/
LLVMValueRef
lp_build_srgb_to_linear(struct gallivm_state *gallivm,
struct lp_type src_type,
unsigned chan_bits,
LLVMValueRef src)
{
struct lp_type f32_type = lp_type_float_vec(32, src_type.length * 32);
struct lp_build_context f32_bld;
LLVMValueRef srcf, part_lin, part_pow, is_linear, lin_const, lin_thresh;
double coeffs[4] = {0.0023f,
0.0030f / 255.0f,
0.6935f / (255.0f * 255.0f),
0.3012f / (255.0f * 255.0f * 255.0f)
};
assert(src_type.width == 32);
/* Technically this would work with more bits too but would be inaccurate. */
assert(chan_bits <= 8);
lp_build_context_init(&f32_bld, gallivm, f32_type);
/*
* using polynomial: (src * (src * (src * 0.3012 + 0.6935) + 0.0030) + 0.0023)
* ( poly = 0.3012*x^3 + 0.6935*x^2 + 0.0030*x + 0.0023)
* (found with octave polyfit and some magic as I couldn't get the error
* function right). Using the above mentioned error function, the values stay
* within +-0.35, except for the lowest values - hence tweaking linear segment
* to cover the first 16 instead of the first 11 values (the error stays
* just about acceptable there too).
* Hence: lin = src > 15 ? poly : src / 12.6
* This function really only makes sense for vectors, should use LUT otherwise.
* All in all (including float conversion) 11 instructions (with sse4.1),
* 6 constants (polynomial could be done with 1 instruction less at the cost
* of slightly worse dependency chain, fma should also help).
*/
/* doing the 1/255 mul as part of the approximation */
srcf = lp_build_int_to_float(&f32_bld, src);
if (chan_bits != 8) {
/* could adjust all the constants instead */
LLVMValueRef rescale_const = lp_build_const_vec(gallivm, f32_type,
255.0f / ((1 << chan_bits) - 1));
srcf = lp_build_mul(&f32_bld, srcf, rescale_const);
}
lin_const = lp_build_const_vec(gallivm, f32_type, 1.0f / (12.6f * 255.0f));
part_lin = lp_build_mul(&f32_bld, srcf, lin_const);
part_pow = lp_build_polynomial(&f32_bld, srcf, coeffs, 4);
lin_thresh = lp_build_const_vec(gallivm, f32_type, 15.0f);
is_linear = lp_build_compare(gallivm, f32_type, PIPE_FUNC_LEQUAL, srcf, lin_thresh);
return lp_build_select(&f32_bld, is_linear, part_lin, part_pow);
}
/**
* Converts int16 half-float to float32
* Note this can be performed in 1 instruction if vcvtph2ps exists (sse5 i think?)
* [llvm.x86.vcvtph2ps / _mm_cvtph_ps]
*
* @param src_type <vector> type of int16
* @param src value to convert
*
* ref http://fgiesen.wordpress.com/2012/03/28/half-to-float-done-quic/
*/
LLVMValueRef
lp_build_half_to_float(struct gallivm_state *gallivm,
struct lp_type src_type,
LLVMValueRef src)
{
struct lp_type f32_type = lp_type_float_vec(32, 32 * src_type.length);
struct lp_type i32_type = lp_type_int_vec(32, 32 * src_type.length);
LLVMBuilderRef builder = gallivm->builder;
LLVMTypeRef int_vec_type = lp_build_vec_type(gallivm, i32_type);
LLVMTypeRef float_vec_type = lp_build_vec_type(gallivm, f32_type);
/* Constants */
LLVMValueRef i32_13 = lp_build_const_int_vec(gallivm, i32_type, 13);
LLVMValueRef i32_16 = lp_build_const_int_vec(gallivm, i32_type, 16);
LLVMValueRef i32_mask_nosign = lp_build_const_int_vec(gallivm, i32_type, 0x7fff);
LLVMValueRef i32_was_infnan = lp_build_const_int_vec(gallivm, i32_type, 0x7bff);
LLVMValueRef i32_exp_infnan = lp_build_const_int_vec(gallivm, i32_type, 0xff << 23);
LLVMValueRef f32_magic = LLVMBuildBitCast(builder,
lp_build_const_int_vec(gallivm, i32_type, (254 - 15) << 23),
float_vec_type, "");
/* Convert int16 vector to int32 vector by zero ext */
LLVMValueRef h = LLVMBuildZExt(builder, src, int_vec_type, "");
/* Exponent / mantissa bits */
LLVMValueRef expmant = LLVMBuildAnd(builder, i32_mask_nosign, h, "");
LLVMValueRef shifted = LLVMBuildBitCast(builder, LLVMBuildShl(builder, expmant, i32_13, ""), float_vec_type, "");
/* Exponent adjust */
LLVMValueRef scaled = LLVMBuildBitCast(builder, LLVMBuildFMul(builder, shifted, f32_magic, ""), int_vec_type, "");
/* Make sure Inf/NaN survive */
LLVMValueRef b_wasinfnan = lp_build_compare(gallivm, i32_type, PIPE_FUNC_GREATER, expmant, i32_was_infnan);
LLVMValueRef infnanexp = LLVMBuildAnd(builder, b_wasinfnan, i32_exp_infnan, "");
/* Sign bit */
LLVMValueRef justsign = LLVMBuildXor(builder, h, expmant, "");
LLVMValueRef sign = LLVMBuildShl(builder, justsign, i32_16, "");
/* Combine result */
LLVMValueRef sign_inf = LLVMBuildOr(builder, sign, infnanexp, "");
LLVMValueRef final = LLVMBuildOr(builder, scaled, sign_inf, "");
/* Cast from int32 vector to float32 vector */
return LLVMBuildBitCast(builder, final, float_vec_type, "");
}
/**
* Register store.
*/
void
lp_emit_store_aos(
struct lp_build_tgsi_aos_context *bld,
const struct tgsi_full_instruction *inst,
unsigned index,
LLVMValueRef value)
{
LLVMBuilderRef builder = bld->bld_base.base.gallivm->builder;
const struct tgsi_full_dst_register *reg = &inst->Dst[index];
LLVMValueRef mask = NULL;
LLVMValueRef ptr;
/*
* Saturate the value
*/
switch (inst->Instruction.Saturate) {
case TGSI_SAT_NONE:
break;
case TGSI_SAT_ZERO_ONE:
value = lp_build_max(&bld->bld_base.base, value, bld->bld_base.base.zero);
value = lp_build_min(&bld->bld_base.base, value, bld->bld_base.base.one);
break;
case TGSI_SAT_MINUS_PLUS_ONE:
value = lp_build_max(&bld->bld_base.base, value, lp_build_const_vec(bld->bld_base.base.gallivm, bld->bld_base.base.type, -1.0));
value = lp_build_min(&bld->bld_base.base, value, bld->bld_base.base.one);
break;
default:
assert(0);
}
/*
* Translate the register file
*/
assert(!reg->Register.Indirect);
switch (reg->Register.File) {
case TGSI_FILE_OUTPUT:
ptr = bld->outputs[reg->Register.Index];
break;
case TGSI_FILE_TEMPORARY:
ptr = bld->temps[reg->Register.Index];
break;
case TGSI_FILE_ADDRESS:
ptr = bld->addr[reg->Indirect.Index];
break;
case TGSI_FILE_PREDICATE:
ptr = bld->preds[reg->Register.Index];
break;
default:
assert(0);
return;
}
if (!ptr)
return;
/*
* Predicate
*/
if (inst->Instruction.Predicate) {
LLVMValueRef pred;
assert(inst->Predicate.Index < LP_MAX_TGSI_PREDS);
pred = LLVMBuildLoad(builder,
bld->preds[inst->Predicate.Index], "");
/*
* Convert the value to an integer mask.
*/
pred = lp_build_compare(bld->bld_base.base.gallivm,
bld->bld_base.base.type,
PIPE_FUNC_NOTEQUAL,
pred,
bld->bld_base.base.zero);
if (inst->Predicate.Negate) {
pred = LLVMBuildNot(builder, pred, "");
}
pred = bld->bld_base.emit_swizzle(&bld->bld_base, pred,
inst->Predicate.SwizzleX,
inst->Predicate.SwizzleY,
inst->Predicate.SwizzleZ,
inst->Predicate.SwizzleW);
if (mask) {
mask = LLVMBuildAnd(builder, mask, pred, "");
} else {
mask = pred;
}
}
/*
* Writemask
*/
if (reg->Register.WriteMask != TGSI_WRITEMASK_XYZW) {
LLVMValueRef writemask;
writemask = lp_build_const_mask_aos_swizzled(bld->bld_base.base.gallivm,
bld->bld_base.base.type,
reg->Register.WriteMask,
TGSI_NUM_CHANNELS,
bld->swizzles);
if (mask) {
mask = LLVMBuildAnd(builder, mask, writemask, "");
} else {
mask = writemask;
}
}
if (mask) {
LLVMValueRef orig_value;
orig_value = LLVMBuildLoad(builder, ptr, "");
value = lp_build_select(&bld->bld_base.base,
mask, value, orig_value);
}
LLVMBuildStore(builder, value, ptr);
}
/**
* Generate the code to do inside/outside triangle testing for the
* four pixels in a 2x2 quad. This will set the four elements of the
* quad mask vector to 0 or ~0.
* \param i which quad of the quad group to test, in [0,3]
*/
static void
generate_tri_edge_mask(LLVMBuilderRef builder,
unsigned i,
LLVMValueRef *mask, /* ivec4, out */
LLVMValueRef c0, /* int32 */
LLVMValueRef c1, /* int32 */
LLVMValueRef c2, /* int32 */
LLVMValueRef step0_ptr, /* ivec4 */
LLVMValueRef step1_ptr, /* ivec4 */
LLVMValueRef step2_ptr) /* ivec4 */
{
#define OPTIMIZE_IN_OUT_TEST 0
#if OPTIMIZE_IN_OUT_TEST
struct lp_build_if_state ifctx;
LLVMValueRef not_draw_all;
#endif
struct lp_build_flow_context *flow;
struct lp_type i32_type;
LLVMTypeRef i32vec4_type, mask_type;
LLVMValueRef c0_vec, c1_vec, c2_vec;
LLVMValueRef in_out_mask;
assert(i < 4);
/* int32 vector type */
memset(&i32_type, 0, sizeof i32_type);
i32_type.floating = FALSE; /* values are integers */
i32_type.sign = TRUE; /* values are signed */
i32_type.norm = FALSE; /* values are not normalized */
i32_type.width = 32; /* 32-bit int values */
i32_type.length = 4; /* 4 elements per vector */
i32vec4_type = lp_build_int32_vec4_type();
mask_type = LLVMIntType(32 * 4);
/*
* Use a conditional here to do detailed pixel in/out testing.
* We only have to do this if c0 != INT_MIN.
*/
flow = lp_build_flow_create(builder);
lp_build_flow_scope_begin(flow);
{
#if OPTIMIZE_IN_OUT_TEST
/* not_draw_all = (c0 != INT_MIN) */
not_draw_all = LLVMBuildICmp(builder,
LLVMIntNE,
c0,
LLVMConstInt(LLVMInt32Type(), INT_MIN, 0),
"");
in_out_mask = lp_build_int_const_scalar(i32_type, ~0);
lp_build_flow_scope_declare(flow, &in_out_mask);
/* if (not_draw_all) {... */
lp_build_if(&ifctx, flow, builder, not_draw_all);
#endif
{
LLVMValueRef step0_vec, step1_vec, step2_vec;
LLVMValueRef m0_vec, m1_vec, m2_vec;
LLVMValueRef index, m;
/* c0_vec = {c0, c0, c0, c0}
* Note that we emit this code four times but LLVM optimizes away
* three instances of it.
*/
c0_vec = lp_build_broadcast(builder, i32vec4_type, c0);
c1_vec = lp_build_broadcast(builder, i32vec4_type, c1);
c2_vec = lp_build_broadcast(builder, i32vec4_type, c2);
lp_build_name(c0_vec, "edgeconst0vec");
lp_build_name(c1_vec, "edgeconst1vec");
lp_build_name(c2_vec, "edgeconst2vec");
/* load step0vec, step1, step2 vec from memory */
index = LLVMConstInt(LLVMInt32Type(), i, 0);
step0_vec = LLVMBuildLoad(builder, LLVMBuildGEP(builder, step0_ptr, &index, 1, ""), "");
step1_vec = LLVMBuildLoad(builder, LLVMBuildGEP(builder, step1_ptr, &index, 1, ""), "");
step2_vec = LLVMBuildLoad(builder, LLVMBuildGEP(builder, step2_ptr, &index, 1, ""), "");
lp_build_name(step0_vec, "step0vec");
lp_build_name(step1_vec, "step1vec");
lp_build_name(step2_vec, "step2vec");
/* m0_vec = step0_ptr[i] > c0_vec */
m0_vec = lp_build_compare(builder, i32_type, PIPE_FUNC_GREATER, step0_vec, c0_vec);
m1_vec = lp_build_compare(builder, i32_type, PIPE_FUNC_GREATER, step1_vec, c1_vec);
m2_vec = lp_build_compare(builder, i32_type, PIPE_FUNC_GREATER, step2_vec, c2_vec);
/* in_out_mask = m0_vec & m1_vec & m2_vec */
m = LLVMBuildAnd(builder, m0_vec, m1_vec, "");
in_out_mask = LLVMBuildAnd(builder, m, m2_vec, "");
lp_build_name(in_out_mask, "inoutmaskvec");
}
#if OPTIMIZE_IN_OUT_TEST
lp_build_endif(&ifctx);
#endif
}
lp_build_flow_scope_end(flow);
lp_build_flow_destroy(flow);
/* This is the initial alive/dead pixel mask for a quad of four pixels.
* It's an int[4] vector with each word set to 0 or ~0.
* Words will get cleared when pixels faile the Z test, etc.
*/
*mask = in_out_mask;
}
/**
* Build LLVM code for texture coord wrapping, for linear filtering,
* for scaled integer texcoords.
* \param block_length is the length of the pixel block along the
* coordinate axis
* \param coord0 the incoming texcoord (s,t,r or q) scaled to the texture size
* \param length the texture size along one dimension
* \param stride pixel stride along the coordinate axis (in bytes)
* \param is_pot if TRUE, length is a power of two
* \param wrap_mode one of PIPE_TEX_WRAP_x
* \param offset0 resulting relative offset for coord0
* \param offset1 resulting relative offset for coord0 + 1
* \param i0 resulting sub-block pixel coordinate for coord0
* \param i1 resulting sub-block pixel coordinate for coord0 + 1
*/
static void
lp_build_sample_wrap_linear_int(struct lp_build_sample_context *bld,
unsigned block_length,
LLVMValueRef coord0,
LLVMValueRef length,
LLVMValueRef stride,
boolean is_pot,
unsigned wrap_mode,
LLVMValueRef *offset0,
LLVMValueRef *offset1,
LLVMValueRef *i0,
LLVMValueRef *i1)
{
struct lp_build_context *int_coord_bld = &bld->int_coord_bld;
LLVMBuilderRef builder = bld->gallivm->builder;
LLVMValueRef length_minus_one;
LLVMValueRef lmask, umask, mask;
if (block_length != 1) {
/*
* If the pixel block covers more than one pixel then there is no easy
* way to calculate offset1 relative to offset0. Instead, compute them
* independently.
*/
LLVMValueRef coord1;
lp_build_sample_wrap_nearest_int(bld,
block_length,
coord0,
length,
stride,
is_pot,
wrap_mode,
offset0, i0);
coord1 = lp_build_add(int_coord_bld, coord0, int_coord_bld->one);
lp_build_sample_wrap_nearest_int(bld,
block_length,
coord1,
length,
stride,
is_pot,
wrap_mode,
offset1, i1);
return;
}
/*
* Scalar pixels -- try to compute offset0 and offset1 with a single stride
* multiplication.
*/
*i0 = int_coord_bld->zero;
*i1 = int_coord_bld->zero;
length_minus_one = lp_build_sub(int_coord_bld, length, int_coord_bld->one);
switch(wrap_mode) {
case PIPE_TEX_WRAP_REPEAT:
if (is_pot) {
coord0 = LLVMBuildAnd(builder, coord0, length_minus_one, "");
}
else {
/* Add a bias to the texcoord to handle negative coords */
LLVMValueRef bias = lp_build_mul_imm(int_coord_bld, length, 1024);
coord0 = LLVMBuildAdd(builder, coord0, bias, "");
coord0 = LLVMBuildURem(builder, coord0, length, "");
}
mask = lp_build_compare(bld->gallivm, int_coord_bld->type,
PIPE_FUNC_NOTEQUAL, coord0, length_minus_one);
*offset0 = lp_build_mul(int_coord_bld, coord0, stride);
*offset1 = LLVMBuildAnd(builder,
lp_build_add(int_coord_bld, *offset0, stride),
mask, "");
break;
case PIPE_TEX_WRAP_CLAMP_TO_EDGE:
lmask = lp_build_compare(int_coord_bld->gallivm, int_coord_bld->type,
PIPE_FUNC_GEQUAL, coord0, int_coord_bld->zero);
umask = lp_build_compare(int_coord_bld->gallivm, int_coord_bld->type,
PIPE_FUNC_LESS, coord0, length_minus_one);
coord0 = lp_build_select(int_coord_bld, lmask, coord0, int_coord_bld->zero);
coord0 = lp_build_select(int_coord_bld, umask, coord0, length_minus_one);
mask = LLVMBuildAnd(builder, lmask, umask, "");
*offset0 = lp_build_mul(int_coord_bld, coord0, stride);
*offset1 = lp_build_add(int_coord_bld,
*offset0,
LLVMBuildAnd(builder, stride, mask, ""));
break;
case PIPE_TEX_WRAP_CLAMP:
case PIPE_TEX_WRAP_CLAMP_TO_BORDER:
case PIPE_TEX_WRAP_MIRROR_REPEAT:
case PIPE_TEX_WRAP_MIRROR_CLAMP:
case PIPE_TEX_WRAP_MIRROR_CLAMP_TO_EDGE:
case PIPE_TEX_WRAP_MIRROR_CLAMP_TO_BORDER:
default:
assert(0);
*offset0 = int_coord_bld->zero;
*offset1 = int_coord_bld->zero;
break;
}
}
/**
* Convert linear float values to srgb int values.
* Several possibilities how to do this, e.g.
* - use table (based on exponent/highest order mantissa bits) and do
* linear interpolation (https://gist.github.com/rygorous/2203834)
* - Chebyshev polynomial
* - Approximation using reciprocals
* - using int-to-float and float-to-int tricks for pow()
* (http://stackoverflow.com/questions/6475373/optimizations-for-pow-with-const-non-integer-exponent)
*
* @param src float (vector) value(s) to convert.
*/
static LLVMValueRef
lp_build_linear_to_srgb(struct gallivm_state *gallivm,
struct lp_type src_type,
LLVMValueRef src)
{
LLVMBuilderRef builder = gallivm->builder;
struct lp_build_context f32_bld;
LLVMValueRef lin_thresh, lin, lin_const, is_linear, tmp, pow_final;
lp_build_context_init(&f32_bld, gallivm, src_type);
src = lp_build_clamp(&f32_bld, src, f32_bld.zero, f32_bld.one);
if (0) {
/*
* using int-to-float and float-to-int trick for pow().
* This is much more accurate than necessary thanks to the correction,
* but it most certainly makes no sense without rsqrt available.
* Bonus points if you understand how this works...
* All in all (including min/max clamp, conversion) 19 instructions.
*/
float exp_f = 2.0f / 3.0f;
/* some compilers can't do exp2f, so this is exp2f(127.0f/exp_f - 127.0f) */
float exp2f_c = 1.30438178253e+19f;
float coeff_f = 0.62996f;
LLVMValueRef pow_approx, coeff, x2, exponent, pow_1, pow_2;
struct lp_type int_type = lp_int_type(src_type);
/*
* First calculate approx x^8/12
*/
exponent = lp_build_const_vec(gallivm, src_type, exp_f);
coeff = lp_build_const_vec(gallivm, src_type,
exp2f_c * powf(coeff_f, 1.0f / exp_f));
/* premultiply src */
tmp = lp_build_mul(&f32_bld, coeff, src);
/* "log2" */
tmp = LLVMBuildBitCast(builder, tmp, lp_build_vec_type(gallivm, int_type), "");
tmp = lp_build_int_to_float(&f32_bld, tmp);
/* multiply for pow */
tmp = lp_build_mul(&f32_bld, tmp, exponent);
/* "exp2" */
pow_approx = lp_build_itrunc(&f32_bld, tmp);
pow_approx = LLVMBuildBitCast(builder, pow_approx,
lp_build_vec_type(gallivm, src_type), "");
/*
* Since that pow was inaccurate (like 3 bits, though each sqrt step would
* give another bit), compensate the error (which is why we chose another
* exponent in the first place).
*/
/* x * x^(8/12) = x^(20/12) */
pow_1 = lp_build_mul(&f32_bld, pow_approx, src);
/* x * x * x^(-4/12) = x^(20/12) */
/* Should avoid using rsqrt if it's not available, but
* using x * x^(4/12) * x^(4/12) instead will change error weight */
tmp = lp_build_fast_rsqrt(&f32_bld, pow_approx);
x2 = lp_build_mul(&f32_bld, src, src);
pow_2 = lp_build_mul(&f32_bld, x2, tmp);
/* average the values so the errors cancel out, compensate bias,
* we also squeeze the 1.055 mul of the srgb conversion plus the 255.0 mul
* for conversion to int in here */
tmp = lp_build_add(&f32_bld, pow_1, pow_2);
coeff = lp_build_const_vec(gallivm, src_type,
1.0f / (3.0f * coeff_f) * 0.999852f *
powf(1.055f * 255.0f, 4.0f));
pow_final = lp_build_mul(&f32_bld, tmp, coeff);
/* x^(5/12) = rsqrt(rsqrt(x^20/12)) */
if (lp_build_fast_rsqrt_available(src_type)) {
pow_final = lp_build_fast_rsqrt(&f32_bld,
lp_build_fast_rsqrt(&f32_bld, pow_final));
}
else {
pow_final = lp_build_sqrt(&f32_bld, lp_build_sqrt(&f32_bld, pow_final));
}
pow_final = lp_build_add(&f32_bld, pow_final,
lp_build_const_vec(gallivm, src_type, -0.055f * 255.0f));
}
else {
/*
* using "rational polynomial" approximation here.
* Essentially y = a*x^0.375 + b*x^0.5 + c, with also
* factoring in the 255.0 mul and the scaling mul.
* (a is closer to actual value so has higher weight than b.)
* Note: the constants are magic values. They were found empirically,
* possibly could be improved but good enough (be VERY careful with
* error metric if you'd want to tweak them, they also MUST fit with
* the crappy polynomial above for srgb->linear since it is required
* that each srgb value maps back to the same value).
* This function has an error of max +-0.17 (and we'd only require +-0.6),
* for the approximated srgb->linear values the error is naturally larger
* (+-0.42) but still accurate enough (required +-0.5 essentially).
* All in all (including min/max clamp, conversion) 15 instructions.
* FMA would help (minus 2 instructions).
*/
LLVMValueRef x05, x0375, a_const, b_const, c_const, tmp2;
if (lp_build_fast_rsqrt_available(src_type)) {
tmp = lp_build_fast_rsqrt(&f32_bld, src);
x05 = lp_build_mul(&f32_bld, src, tmp);
}
else {
/*
* I don't really expect this to be practical without rsqrt
* but there's no reason for triple punishment so at least
* save the otherwise resulting division and unnecessary mul...
*/
x05 = lp_build_sqrt(&f32_bld, src);
}
tmp = lp_build_mul(&f32_bld, x05, src);
if (lp_build_fast_rsqrt_available(src_type)) {
x0375 = lp_build_fast_rsqrt(&f32_bld, lp_build_fast_rsqrt(&f32_bld, tmp));
}
else {
x0375 = lp_build_sqrt(&f32_bld, lp_build_sqrt(&f32_bld, tmp));
}
a_const = lp_build_const_vec(gallivm, src_type, 0.675f * 1.0622 * 255.0f);
b_const = lp_build_const_vec(gallivm, src_type, 0.325f * 1.0622 * 255.0f);
c_const = lp_build_const_vec(gallivm, src_type, -0.0620f * 255.0f);
tmp = lp_build_mul(&f32_bld, a_const, x0375);
tmp2 = lp_build_mul(&f32_bld, b_const, x05);
tmp2 = lp_build_add(&f32_bld, tmp2, c_const);
pow_final = lp_build_add(&f32_bld, tmp, tmp2);
}
/* linear part is easy */
lin_const = lp_build_const_vec(gallivm, src_type, 12.92f * 255.0f);
lin = lp_build_mul(&f32_bld, src, lin_const);
lin_thresh = lp_build_const_vec(gallivm, src_type, 0.0031308f);
is_linear = lp_build_compare(gallivm, src_type, PIPE_FUNC_LEQUAL, src, lin_thresh);
tmp = lp_build_select(&f32_bld, is_linear, lin, pow_final);
f32_bld.type.sign = 0;
return lp_build_iround(&f32_bld, tmp);
}
/**
* Expand the relevent bits of mask_input to a 4-dword mask for the
* four pixels in a 2x2 quad. This will set the four elements of the
* quad mask vector to 0 or ~0.
*
* \param quad which quad of the quad group to test, in [0,3]
* \param mask_input bitwise mask for the whole 4x4 stamp
*/
static LLVMValueRef
generate_quad_mask(LLVMBuilderRef builder,
struct lp_type fs_type,
unsigned quad,
LLVMValueRef mask_input) /* int32 */
{
struct lp_type mask_type;
LLVMTypeRef i32t = LLVMInt32Type();
LLVMValueRef bits[4];
LLVMValueRef mask;
int shift;
/*
* XXX: We'll need a different path for 16 x u8
*/
assert(fs_type.width == 32);
assert(fs_type.length == 4);
mask_type = lp_int_type(fs_type);
/*
* mask_input >>= (quad * 4)
*/
switch (quad) {
case 0:
shift = 0;
break;
case 1:
shift = 2;
break;
case 2:
shift = 8;
break;
case 3:
shift = 10;
break;
default:
assert(0);
shift = 0;
}
mask_input = LLVMBuildLShr(builder,
mask_input,
LLVMConstInt(i32t, shift, 0),
"");
/*
* mask = { mask_input & (1 << i), for i in [0,3] }
*/
mask = lp_build_broadcast(builder, lp_build_vec_type(mask_type), mask_input);
bits[0] = LLVMConstInt(i32t, 1 << 0, 0);
bits[1] = LLVMConstInt(i32t, 1 << 1, 0);
bits[2] = LLVMConstInt(i32t, 1 << 4, 0);
bits[3] = LLVMConstInt(i32t, 1 << 5, 0);
mask = LLVMBuildAnd(builder, mask, LLVMConstVector(bits, 4), "");
/*
* mask = mask != 0 ? ~0 : 0
*/
mask = lp_build_compare(builder,
mask_type, PIPE_FUNC_NOTEQUAL,
mask,
lp_build_const_int_vec(mask_type, 0));
return mask;
}