radeonsi: separate code computing info for small primitive culling

[mesa.git] / src / gallium / drivers / radeonsi / si_state_viewport.c

/*
 * Copyright 2012 Advanced Micro Devices, Inc.
 * All Rights Reserved.
 *
 * 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
 * on the rights to use, copy, modify, merge, publish, distribute, sub
 * license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHOR(S) AND/OR THEIR SUPPLIERS 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 "si_build_pm4.h"
#include "util/u_viewport.h"

#define SI_MAX_SCISSOR 16384

void si_get_small_prim_cull_info(struct si_context *sctx,
                                 struct si_small_prim_cull_info *out)
{
        /* This is needed by the small primitive culling, because it's done
         * in screen space.
         */
        struct si_small_prim_cull_info info;
        unsigned num_samples = sctx->framebuffer.nr_samples;
        assert(num_samples >= 1);

        info.scale[0] = sctx->viewports.states[0].scale[0];
        info.scale[1] = sctx->viewports.states[0].scale[1];
        info.translate[0] = sctx->viewports.states[0].translate[0];
        info.translate[1] = sctx->viewports.states[0].translate[1];

        /* The viewport shouldn't flip the X axis for the small prim culling to work. */
        assert(-info.scale[0] + info.translate[0] <= info.scale[0] + info.translate[0]);

        /* If the Y axis is inverted (OpenGL default framebuffer), reverse it.
         * This is because the viewport transformation inverts the clip space
         * bounding box, so min becomes max, which breaks small primitive
         * culling.
         */
        if (sctx->viewports.y_inverted) {
                info.scale[1] = -info.scale[1];
                info.translate[1] = -info.translate[1];
        }

        /* Scale the framebuffer up, so that samples become pixels and small
         * primitive culling is the same for all sample counts.
         * This only works with the standard DX sample positions, because
         * the samples are evenly spaced on both X and Y axes.
         */
        for (unsigned i = 0; i < 2; i++) {
                info.scale[i] *= num_samples;
                info.translate[i] *= num_samples;
        }
        *out = info;
}

static void si_set_scissor_states(struct pipe_context *pctx,
                                  unsigned start_slot,
                                  unsigned num_scissors,
                                  const struct pipe_scissor_state *state)
{
        struct si_context *ctx = (struct si_context *)pctx;
        int i;

        for (i = 0; i < num_scissors; i++)
                ctx->scissors[start_slot + i] = state[i];

        if (!ctx->queued.named.rasterizer->scissor_enable)
                return;

        si_mark_atom_dirty(ctx, &ctx->atoms.s.scissors);
}

/* Since the guard band disables clipping, we have to clip per-pixel
 * using a scissor.
 */
static void si_get_scissor_from_viewport(struct si_context *ctx,
                                         const struct pipe_viewport_state *vp,
                                         struct si_signed_scissor *scissor)
{
        float tmp, minx, miny, maxx, maxy;

        /* Convert (-1, -1) and (1, 1) from clip space into window space. */
        minx = -vp->scale[0] + vp->translate[0];
        miny = -vp->scale[1] + vp->translate[1];
        maxx = vp->scale[0] + vp->translate[0];
        maxy = vp->scale[1] + vp->translate[1];

        /* Handle inverted viewports. */
        if (minx > maxx) {
                tmp = minx;
                minx = maxx;
                maxx = tmp;
        }
        if (miny > maxy) {
                tmp = miny;
                miny = maxy;
                maxy = tmp;
        }

        /* Convert to integer and round up the max bounds. */
        scissor->minx = minx;
        scissor->miny = miny;
        scissor->maxx = ceilf(maxx);
        scissor->maxy = ceilf(maxy);
}

static void si_clamp_scissor(struct si_context *ctx,
                             struct pipe_scissor_state *out,
                             struct si_signed_scissor *scissor)
{
        out->minx = CLAMP(scissor->minx, 0, SI_MAX_SCISSOR);
        out->miny = CLAMP(scissor->miny, 0, SI_MAX_SCISSOR);
        out->maxx = CLAMP(scissor->maxx, 0, SI_MAX_SCISSOR);
        out->maxy = CLAMP(scissor->maxy, 0, SI_MAX_SCISSOR);
}

static void si_clip_scissor(struct pipe_scissor_state *out,
                            struct pipe_scissor_state *clip)
{
        out->minx = MAX2(out->minx, clip->minx);
        out->miny = MAX2(out->miny, clip->miny);
        out->maxx = MIN2(out->maxx, clip->maxx);
        out->maxy = MIN2(out->maxy, clip->maxy);
}

static void si_scissor_make_union(struct si_signed_scissor *out,
                                  struct si_signed_scissor *in)
{
        out->minx = MIN2(out->minx, in->minx);
        out->miny = MIN2(out->miny, in->miny);
        out->maxx = MAX2(out->maxx, in->maxx);
        out->maxy = MAX2(out->maxy, in->maxy);
        out->quant_mode = MIN2(out->quant_mode, in->quant_mode);
}

static void si_emit_one_scissor(struct si_context *ctx,
                                struct radeon_cmdbuf *cs,
                                struct si_signed_scissor *vp_scissor,
                                struct pipe_scissor_state *scissor)
{
        struct pipe_scissor_state final;

        if (ctx->vs_disables_clipping_viewport) {
                final.minx = final.miny = 0;
                final.maxx = final.maxy = SI_MAX_SCISSOR;
        } else {
                si_clamp_scissor(ctx, &final, vp_scissor);
        }

        if (scissor)
                si_clip_scissor(&final, scissor);

        /* Workaround for a hw bug on GFX6 that occurs when PA_SU_HARDWARE_-
         * SCREEN_OFFSET != 0 and any_scissor.BR_X/Y <= 0.
         */
        if (ctx->chip_class == GFX6 && (final.maxx == 0 || final.maxy == 0)) {
                radeon_emit(cs, S_028250_TL_X(1) |
                                S_028250_TL_Y(1) |
                                S_028250_WINDOW_OFFSET_DISABLE(1));
                radeon_emit(cs, S_028254_BR_X(1) |
                                S_028254_BR_Y(1));
                return;
        }

        radeon_emit(cs, S_028250_TL_X(final.minx) |
                        S_028250_TL_Y(final.miny) |
                        S_028250_WINDOW_OFFSET_DISABLE(1));
        radeon_emit(cs, S_028254_BR_X(final.maxx) |
                        S_028254_BR_Y(final.maxy));
}

#define MAX_PA_SU_HARDWARE_SCREEN_OFFSET 8176

static void si_emit_guardband(struct si_context *ctx)
{
        const struct si_state_rasterizer *rs = ctx->queued.named.rasterizer;
        struct si_signed_scissor vp_as_scissor;
        struct pipe_viewport_state vp;
        float left, top, right, bottom, max_range, guardband_x, guardband_y;
        float discard_x, discard_y;

        if (ctx->vs_writes_viewport_index) {
                /* Shaders can draw to any viewport. Make a union of all
                 * viewports. */
                vp_as_scissor = ctx->viewports.as_scissor[0];
                for (unsigned i = 1; i < SI_MAX_VIEWPORTS; i++) {
                        si_scissor_make_union(&vp_as_scissor,
                                              &ctx->viewports.as_scissor[i]);
                }
        } else {
                vp_as_scissor = ctx->viewports.as_scissor[0];
        }

        /* Blits don't set the viewport state. The vertex shader determines
         * the viewport size by scaling the coordinates, so we don't know
         * how large the viewport is. Assume the worst case.
         */
        if (ctx->vs_disables_clipping_viewport)
                vp_as_scissor.quant_mode = SI_QUANT_MODE_16_8_FIXED_POINT_1_256TH;

        /* Determine the optimal hardware screen offset to center the viewport
         * within the viewport range in order to maximize the guardband size.
         */
        int hw_screen_offset_x = (vp_as_scissor.maxx + vp_as_scissor.minx) / 2;
        int hw_screen_offset_y = (vp_as_scissor.maxy + vp_as_scissor.miny) / 2;

        /* GFX6-GFX7 need to align the offset to an ubertile consisting of all SEs. */
        const unsigned hw_screen_offset_alignment =
                ctx->chip_class >= GFX8 ? 16 : MAX2(ctx->screen->se_tile_repeat, 16);

        /* Indexed by quantization modes */
        static int max_viewport_size[] = {65535, 16383, 4095};

        /* Ensure that the whole viewport stays representable in
         * absolute coordinates.
         * See comment in si_set_viewport_states.
         */
        assert(vp_as_scissor.maxx <= max_viewport_size[vp_as_scissor.quant_mode] &&
               vp_as_scissor.maxy <= max_viewport_size[vp_as_scissor.quant_mode]);

        hw_screen_offset_x = CLAMP(hw_screen_offset_x, 0, MAX_PA_SU_HARDWARE_SCREEN_OFFSET);
        hw_screen_offset_y = CLAMP(hw_screen_offset_y, 0, MAX_PA_SU_HARDWARE_SCREEN_OFFSET);

        /* Align the screen offset by dropping the low bits. */
        hw_screen_offset_x &= ~(hw_screen_offset_alignment - 1);
        hw_screen_offset_y &= ~(hw_screen_offset_alignment - 1);

        /* Apply the offset to center the viewport and maximize the guardband. */
        vp_as_scissor.minx -= hw_screen_offset_x;
        vp_as_scissor.maxx -= hw_screen_offset_x;
        vp_as_scissor.miny -= hw_screen_offset_y;
        vp_as_scissor.maxy -= hw_screen_offset_y;

        /* Reconstruct the viewport transformation from the scissor. */
        vp.translate[0] = (vp_as_scissor.minx + vp_as_scissor.maxx) / 2.0;
        vp.translate[1] = (vp_as_scissor.miny + vp_as_scissor.maxy) / 2.0;
        vp.scale[0] = vp_as_scissor.maxx - vp.translate[0];
        vp.scale[1] = vp_as_scissor.maxy - vp.translate[1];

        /* Treat a 0x0 viewport as 1x1 to prevent division by zero. */
        if (vp_as_scissor.minx == vp_as_scissor.maxx)
                vp.scale[0] = 0.5;
        if (vp_as_scissor.miny == vp_as_scissor.maxy)
                vp.scale[1] = 0.5;

        /* Find the biggest guard band that is inside the supported viewport
         * range. The guard band is specified as a horizontal and vertical
         * distance from (0,0) in clip space.
         *
         * This is done by applying the inverse viewport transformation
         * on the viewport limits to get those limits in clip space.
         *
         * The viewport range is [-max_viewport_size/2, max_viewport_size/2].
         */
        assert(vp_as_scissor.quant_mode < ARRAY_SIZE(max_viewport_size));
        max_range = max_viewport_size[vp_as_scissor.quant_mode] / 2;
        left   = (-max_range - vp.translate[0]) / vp.scale[0];
        right  = ( max_range - vp.translate[0]) / vp.scale[0];
        top    = (-max_range - vp.translate[1]) / vp.scale[1];
        bottom = ( max_range - vp.translate[1]) / vp.scale[1];

        assert(left <= -1 && top <= -1 && right >= 1 && bottom >= 1);

        guardband_x = MIN2(-left, right);
        guardband_y = MIN2(-top, bottom);

        discard_x = 1.0;
        discard_y = 1.0;

        if (unlikely(util_prim_is_points_or_lines(ctx->current_rast_prim))) {
                /* When rendering wide points or lines, we need to be more
                 * conservative about when to discard them entirely. */
                float pixels;

                if (ctx->current_rast_prim == PIPE_PRIM_POINTS)
                        pixels = rs->max_point_size;
                else
                        pixels = rs->line_width;

                /* Add half the point size / line width */
                discard_x += pixels / (2.0 * vp.scale[0]);
                discard_y += pixels / (2.0 * vp.scale[1]);

                /* Discard primitives that would lie entirely outside the clip
                 * region. */
                discard_x = MIN2(discard_x, guardband_x);
                discard_y = MIN2(discard_y, guardband_y);
        }

        /* If any of the GB registers is updated, all of them must be updated.
         * R_028BE8_PA_CL_GB_VERT_CLIP_ADJ, R_028BEC_PA_CL_GB_VERT_DISC_ADJ
         * R_028BF0_PA_CL_GB_HORZ_CLIP_ADJ, R_028BF4_PA_CL_GB_HORZ_DISC_ADJ
         */
        unsigned initial_cdw = ctx->gfx_cs->current.cdw;
        radeon_opt_set_context_reg4(ctx, R_028BE8_PA_CL_GB_VERT_CLIP_ADJ,
                                    SI_TRACKED_PA_CL_GB_VERT_CLIP_ADJ,
                                    fui(guardband_y), fui(discard_y),
                                    fui(guardband_x), fui(discard_x));
        radeon_opt_set_context_reg(ctx, R_028234_PA_SU_HARDWARE_SCREEN_OFFSET,
                                   SI_TRACKED_PA_SU_HARDWARE_SCREEN_OFFSET,
                                   S_028234_HW_SCREEN_OFFSET_X(hw_screen_offset_x >> 4) |
                                   S_028234_HW_SCREEN_OFFSET_Y(hw_screen_offset_y >> 4));
        radeon_opt_set_context_reg(ctx, R_028BE4_PA_SU_VTX_CNTL,
                                   SI_TRACKED_PA_SU_VTX_CNTL,
                                   S_028BE4_PIX_CENTER(rs->half_pixel_center) |
                                   S_028BE4_QUANT_MODE(V_028BE4_X_16_8_FIXED_POINT_1_256TH +
                                                       vp_as_scissor.quant_mode));
        if (initial_cdw != ctx->gfx_cs->current.cdw)
                ctx->context_roll = true;
}

static void si_emit_scissors(struct si_context *ctx)
{
        struct radeon_cmdbuf *cs = ctx->gfx_cs;
        struct pipe_scissor_state *states = ctx->scissors;
        bool scissor_enabled = ctx->queued.named.rasterizer->scissor_enable;

        /* The simple case: Only 1 viewport is active. */
        if (!ctx->vs_writes_viewport_index) {
                struct si_signed_scissor *vp = &ctx->viewports.as_scissor[0];

                radeon_set_context_reg_seq(cs, R_028250_PA_SC_VPORT_SCISSOR_0_TL, 2);
                si_emit_one_scissor(ctx, cs, vp, scissor_enabled ? &states[0] : NULL);
                return;
        }

        /* All registers in the array need to be updated if any of them is changed.
         * This is a hardware requirement.
         */
        radeon_set_context_reg_seq(cs, R_028250_PA_SC_VPORT_SCISSOR_0_TL,
                                   SI_MAX_VIEWPORTS * 2);
        for (unsigned i = 0; i < SI_MAX_VIEWPORTS; i++) {
                si_emit_one_scissor(ctx, cs, &ctx->viewports.as_scissor[i],
                                    scissor_enabled ? &states[i] : NULL);
        }
}

static void si_set_viewport_states(struct pipe_context *pctx,
                                   unsigned start_slot,
                                   unsigned num_viewports,
                                   const struct pipe_viewport_state *state)
{
        struct si_context *ctx = (struct si_context *)pctx;
        int i;

        for (i = 0; i < num_viewports; i++) {
                unsigned index = start_slot + i;
                struct si_signed_scissor *scissor = &ctx->viewports.as_scissor[index];

                ctx->viewports.states[index] = state[i];

                si_get_scissor_from_viewport(ctx, &state[i], scissor);

                unsigned w = scissor->maxx - scissor->minx;
                unsigned h = scissor->maxy - scissor->miny;
                unsigned max_extent = MAX2(w, h);

                int max_corner = MAX2(scissor->maxx, scissor->maxy);

                unsigned center_x = (scissor->maxx + scissor->minx) / 2;
                unsigned center_y = (scissor->maxy + scissor->miny) / 2;
                unsigned max_center = MAX2(center_x, center_y);

                /* PA_SU_HARDWARE_SCREEN_OFFSET can't center viewports whose
                 * center start farther than MAX_PA_SU_HARDWARE_SCREEN_OFFSET.
                 * (for example, a 1x1 viewport in the lower right corner of
                 * 16Kx16K) Such viewports need a greater guardband, so they
                 * have to use a worse quantization mode.
                 */
                unsigned distance_off_center =
                        MAX2(0, (int)max_center - MAX_PA_SU_HARDWARE_SCREEN_OFFSET);
                max_extent += distance_off_center;

                /* Determine the best quantization mode (subpixel precision),
                 * but also leave enough space for the guardband.
                 *
                 * Note that primitive binning requires QUANT_MODE == 16_8 on Vega10
                 * and Raven1 for line and rectangle primitive types to work correctly.
                 * Always use 16_8 if primitive binning is possible to occur.
                 */
                if ((ctx->family == CHIP_VEGA10 || ctx->family == CHIP_RAVEN) &&
                    ctx->screen->dpbb_allowed)
                        max_extent = 16384; /* Use QUANT_MODE == 16_8. */

                /* Another constraint is that all coordinates in the viewport
                 * are representable in fixed point with respect to the
                 * surface origin.
                 *
                 * It means that PA_SU_HARDWARE_SCREEN_OFFSET can't be given
                 * an offset that would make the upper corner of the viewport
                 * greater than the maximum representable number post
                 * quantization, ie 2^quant_bits.
                 *
                 * This does not matter for 14.10 and 16.8 formats since the
                 * offset is already limited at 8k, but it means we can't use
                 * 12.12 if we are drawing to some pixels outside the lower
                 * 4k x 4k of the render target.
                 */

                if (max_extent <= 1024 && max_corner < 4096) /* 4K scanline area for guardband */
                        scissor->quant_mode = SI_QUANT_MODE_12_12_FIXED_POINT_1_4096TH;
                else if (max_extent <= 4096) /* 16K scanline area for guardband */
                        scissor->quant_mode = SI_QUANT_MODE_14_10_FIXED_POINT_1_1024TH;
                else /* 64K scanline area for guardband */
                        scissor->quant_mode = SI_QUANT_MODE_16_8_FIXED_POINT_1_256TH;
        }

        if (start_slot == 0) {
                ctx->viewports.y_inverted =
                        -state->scale[1] + state->translate[1] >
                        state->scale[1] + state->translate[1];
        }

        si_mark_atom_dirty(ctx, &ctx->atoms.s.viewports);
        si_mark_atom_dirty(ctx, &ctx->atoms.s.guardband);
        si_mark_atom_dirty(ctx, &ctx->atoms.s.scissors);
}

static void si_emit_one_viewport(struct si_context *ctx,
                                 struct pipe_viewport_state *state)
{
        struct radeon_cmdbuf *cs = ctx->gfx_cs;

        radeon_emit(cs, fui(state->scale[0]));
        radeon_emit(cs, fui(state->translate[0]));
        radeon_emit(cs, fui(state->scale[1]));
        radeon_emit(cs, fui(state->translate[1]));
        radeon_emit(cs, fui(state->scale[2]));
        radeon_emit(cs, fui(state->translate[2]));
}

static void si_emit_viewports(struct si_context *ctx)
{
        struct radeon_cmdbuf *cs = ctx->gfx_cs;
        struct pipe_viewport_state *states = ctx->viewports.states;

        /* The simple case: Only 1 viewport is active. */
        if (!ctx->vs_writes_viewport_index) {
                radeon_set_context_reg_seq(cs, R_02843C_PA_CL_VPORT_XSCALE, 6);
                si_emit_one_viewport(ctx, &states[0]);
                return;
        }

        /* All registers in the array need to be updated if any of them is changed.
         * This is a hardware requirement.
         */
        radeon_set_context_reg_seq(cs, R_02843C_PA_CL_VPORT_XSCALE +
                                   0, SI_MAX_VIEWPORTS * 6);
        for (unsigned i = 0; i < SI_MAX_VIEWPORTS; i++)
                si_emit_one_viewport(ctx, &states[i]);
}

static inline void
si_viewport_zmin_zmax(const struct pipe_viewport_state *vp, bool halfz,
                      bool window_space_position, float *zmin, float *zmax)
{
        if (window_space_position) {
                *zmin = 0;
                *zmax = 1;
                return;
        }
        util_viewport_zmin_zmax(vp, halfz, zmin, zmax);
}

static void si_emit_depth_ranges(struct si_context *ctx)
{
        struct radeon_cmdbuf *cs = ctx->gfx_cs;
        struct pipe_viewport_state *states = ctx->viewports.states;
        bool clip_halfz = ctx->queued.named.rasterizer->clip_halfz;
        bool window_space = ctx->vs_disables_clipping_viewport;
        float zmin, zmax;

        /* The simple case: Only 1 viewport is active. */
        if (!ctx->vs_writes_viewport_index) {
                si_viewport_zmin_zmax(&states[0], clip_halfz, window_space,
                                      &zmin, &zmax);

                radeon_set_context_reg_seq(cs, R_0282D0_PA_SC_VPORT_ZMIN_0, 2);
                radeon_emit(cs, fui(zmin));
                radeon_emit(cs, fui(zmax));
                return;
        }

        /* All registers in the array need to be updated if any of them is changed.
         * This is a hardware requirement.
         */
        radeon_set_context_reg_seq(cs, R_0282D0_PA_SC_VPORT_ZMIN_0,
                                   SI_MAX_VIEWPORTS * 2);
        for (unsigned i = 0; i < SI_MAX_VIEWPORTS; i++) {
                si_viewport_zmin_zmax(&states[i], clip_halfz, window_space,
                                      &zmin, &zmax);
                radeon_emit(cs, fui(zmin));
                radeon_emit(cs, fui(zmax));
        }
}

static void si_emit_viewport_states(struct si_context *ctx)
{
        si_emit_viewports(ctx);
        si_emit_depth_ranges(ctx);
}

/**
 * This reacts to 2 state changes:
 * - VS.writes_viewport_index
 * - VS output position in window space (enable/disable)
 *
 * Normally, we only emit 1 viewport and 1 scissor if no shader is using
 * the VIEWPORT_INDEX output, and emitting the other viewports and scissors
 * is delayed. When a shader with VIEWPORT_INDEX appears, this should be
 * called to emit the rest.
 */
void si_update_vs_viewport_state(struct si_context *ctx)
{
        struct si_shader_info *info = si_get_vs_info(ctx);
        bool vs_window_space;

        if (!info)
                return;

        /* When the VS disables clipping and viewport transformation. */
        vs_window_space =
                info->properties[TGSI_PROPERTY_VS_WINDOW_SPACE_POSITION];

        if (ctx->vs_disables_clipping_viewport != vs_window_space) {
                ctx->vs_disables_clipping_viewport = vs_window_space;
                si_mark_atom_dirty(ctx, &ctx->atoms.s.scissors);
                si_mark_atom_dirty(ctx, &ctx->atoms.s.viewports);
        }

        /* Viewport index handling. */
        if (ctx->vs_writes_viewport_index == info->writes_viewport_index)
                return;

        /* This changes how the guardband is computed. */
        ctx->vs_writes_viewport_index = info->writes_viewport_index;
        si_mark_atom_dirty(ctx, &ctx->atoms.s.guardband);

        /* Emit scissors and viewports that were enabled by having
         * the ViewportIndex output.
         */
        if (info->writes_viewport_index) {
            si_mark_atom_dirty(ctx, &ctx->atoms.s.scissors);
            si_mark_atom_dirty(ctx, &ctx->atoms.s.viewports);
        }
}

static void si_emit_window_rectangles(struct si_context *sctx)
{
        /* There are four clipping rectangles. Their corner coordinates are inclusive.
         * Every pixel is assigned a number from 0 and 15 by setting bits 0-3 depending
         * on whether the pixel is inside cliprects 0-3, respectively. For example,
         * if a pixel is inside cliprects 0 and 1, but outside 2 and 3, it is assigned
         * the number 3 (binary 0011).
         *
         * If CLIPRECT_RULE & (1 << number), the pixel is rasterized.
         */
        struct radeon_cmdbuf *cs = sctx->gfx_cs;
        static const unsigned outside[4] = {
                /* outside rectangle 0 */
                V_02820C_OUT |
                V_02820C_IN_1 |
                V_02820C_IN_2 |
                V_02820C_IN_21 |
                V_02820C_IN_3 |
                V_02820C_IN_31 |
                V_02820C_IN_32 |
                V_02820C_IN_321,
                /* outside rectangles 0, 1 */
                V_02820C_OUT |
                V_02820C_IN_2 |
                V_02820C_IN_3 |
                V_02820C_IN_32,
                /* outside rectangles 0, 1, 2 */
                V_02820C_OUT |
                V_02820C_IN_3,
                /* outside rectangles 0, 1, 2, 3 */
                V_02820C_OUT,
        };
        const unsigned disabled = 0xffff; /* all inside and outside cases */
        unsigned num_rectangles = sctx->num_window_rectangles;
        struct pipe_scissor_state *rects = sctx->window_rectangles;
        unsigned rule;

        assert(num_rectangles <= 4);

        if (num_rectangles == 0)
                rule = disabled;
        else if (sctx->window_rectangles_include)
                rule = ~outside[num_rectangles - 1];
        else
                rule = outside[num_rectangles - 1];

        radeon_opt_set_context_reg(sctx, R_02820C_PA_SC_CLIPRECT_RULE,
                                   SI_TRACKED_PA_SC_CLIPRECT_RULE, rule);
        if (num_rectangles == 0)
                return;

        radeon_set_context_reg_seq(cs, R_028210_PA_SC_CLIPRECT_0_TL,
                                   num_rectangles * 2);
        for (unsigned i = 0; i < num_rectangles; i++) {
                radeon_emit(cs, S_028210_TL_X(rects[i].minx) |
                                S_028210_TL_Y(rects[i].miny));
                radeon_emit(cs, S_028214_BR_X(rects[i].maxx) |
                                S_028214_BR_Y(rects[i].maxy));
        }
}

static void si_set_window_rectangles(struct pipe_context *ctx,
                                     bool include,
                                     unsigned num_rectangles,
                                     const struct pipe_scissor_state *rects)
{
        struct si_context *sctx = (struct si_context *)ctx;

        sctx->num_window_rectangles = num_rectangles;
        sctx->window_rectangles_include = include;
        if (num_rectangles) {
                memcpy(sctx->window_rectangles, rects,
                       sizeof(*rects) * num_rectangles);
        }

        si_mark_atom_dirty(sctx, &sctx->atoms.s.window_rectangles);
}

void si_init_viewport_functions(struct si_context *ctx)
{
        ctx->atoms.s.guardband.emit = si_emit_guardband;
        ctx->atoms.s.scissors.emit = si_emit_scissors;
        ctx->atoms.s.viewports.emit = si_emit_viewport_states;
        ctx->atoms.s.window_rectangles.emit = si_emit_window_rectangles;

        ctx->b.set_scissor_states = si_set_scissor_states;
        ctx->b.set_viewport_states = si_set_viewport_states;
        ctx->b.set_window_rectangles = si_set_window_rectangles;

        for (unsigned i = 0; i < 16; i++)
                ctx->viewports.as_scissor[i].quant_mode = SI_QUANT_MODE_16_8_FIXED_POINT_1_256TH;
}