intel: improve command decoding

Decode both batch and state buffers.  Decoding is enabled with
INTEL_DEBUG=batch for now.  The functionality should be moved to the debug
layer in the future.
diff --git a/icd/intel/cmd_decode.c b/icd/intel/cmd_decode.c
new file mode 100644
index 0000000..cc1e1f8
--- /dev/null
+++ b/icd/intel/cmd_decode.c
@@ -0,0 +1,578 @@
+/*
+ * Mesa 3-D graphics library
+ *
+ * Copyright (C) 2014 LunarG, Inc.
+ *
+ * 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 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.
+ *
+ * Authors:
+ *    Chia-I Wu <olv@lunarg.com>
+ */
+
+#include <stdio.h>
+#include <stdarg.h>
+#include "genhw/genhw.h"
+#include "kmd/winsys.h"
+#include "cmd_priv.h"
+
+#define READ(dw, field) (((dw) & field ## __MASK) >> field ## __SHIFT)
+
+static const uint32_t *
+writer_pointer(const struct intel_cmd *cmd,
+               enum intel_cmd_writer_type which,
+               unsigned offset)
+{
+    const struct intel_cmd_writer *writer = &cmd->writers[which];
+    return (const uint32_t *) ((const char *) writer->ptr + offset);
+}
+
+static uint32_t
+writer_dw(const struct intel_cmd *cmd,
+          enum intel_cmd_writer_type which,
+          unsigned offset, unsigned dw_index,
+          const char *format, ...)
+{
+    const uint32_t *dw = writer_pointer(cmd, which, offset);
+    va_list ap;
+    char desc[16];
+    int len;
+
+    fprintf(stderr, "0x%08x:      0x%08x: ",
+            offset + (dw_index << 2), dw[dw_index]);
+
+    va_start(ap, format);
+    len = vsnprintf(desc, sizeof(desc), format, ap);
+    va_end(ap);
+
+    if (len >= sizeof(desc)) {
+        len = sizeof(desc) - 1;
+        desc[len] = '\0';
+    }
+
+    if (desc[len - 1] == '\n') {
+        desc[len - 1] = '\0';
+        fprintf(stderr, "%8s: \n", desc);
+    } else {
+        fprintf(stderr, "%8s: ", desc);
+    }
+
+    return dw[dw_index];
+}
+
+static void
+writer_decode_blob(const struct intel_cmd *cmd,
+                   enum intel_cmd_writer_type which,
+                   const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 4;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        const uint32_t *dw = writer_pointer(cmd, which, offset);
+
+        writer_dw(cmd, which, offset, 0, "BLOB%d", i);
+        /* output a single line for all four DWords */
+        fprintf(stderr, "(% f, % f, % f, % f) "
+                        "(0x%08x, 0x%08x, 0x%08x, 0x%08x)\n",
+                        u_uif(dw[0]), u_uif(dw[1]), u_uif(dw[2]), u_uif(dw[3]),
+                        dw[0], dw[1], dw[2], dw[3]);
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_clip_viewport(const struct intel_cmd *cmd,
+                            enum intel_cmd_writer_type which,
+                            const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 4;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        uint32_t dw;
+
+        dw = writer_dw(cmd, which, offset, 0, "CLIP VP%d", i);
+        fprintf(stderr, "xmin = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 1, "CLIP VP%d", i);
+        fprintf(stderr, "xmax = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 2, "CLIP VP%d", i);
+        fprintf(stderr, "ymin = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 3, "CLIP VP%d", i);
+        fprintf(stderr, "ymax = %f\n", u_uif(dw));
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_sf_clip_viewport_gen7(const struct intel_cmd *cmd,
+                                    enum intel_cmd_writer_type which,
+                                    const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 16;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        uint32_t dw;
+
+        dw = writer_dw(cmd, which, offset, 0, "SF_CLIP VP%d", i);
+        fprintf(stderr, "m00 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 1, "SF_CLIP VP%d", i);
+        fprintf(stderr, "m11 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 2, "SF_CLIP VP%d", i);
+        fprintf(stderr, "m22 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 3, "SF_CLIP VP%d", i);
+        fprintf(stderr, "m30 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 4, "SF_CLIP VP%d", i);
+        fprintf(stderr, "m31 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 5, "SF_CLIP VP%d", i);
+        fprintf(stderr, "m32 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 8, "SF_CLIP VP%d", i);
+        fprintf(stderr, "guardband xmin = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 9, "SF_CLIP VP%d", i);
+        fprintf(stderr, "guardband xmax = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 10, "SF_CLIP VP%d", i);
+        fprintf(stderr, "guardband ymin = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 11, "SF_CLIP VP%d", i);
+        fprintf(stderr, "guardband ymax = %f\n", u_uif(dw));
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_sf_viewport_gen6(const struct intel_cmd *cmd,
+                               enum intel_cmd_writer_type which,
+                               const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 8;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        uint32_t dw;
+
+        dw = writer_dw(cmd, which, offset, 0, "SF VP%d", i);
+        fprintf(stderr, "m00 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 1, "SF VP%d", i);
+        fprintf(stderr, "m11 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 2, "SF VP%d", i);
+        fprintf(stderr, "m22 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 3, "SF VP%d", i);
+        fprintf(stderr, "m30 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 4, "SF VP%d", i);
+        fprintf(stderr, "m31 = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 5, "SF VP%d", i);
+        fprintf(stderr, "m32 = %f\n", u_uif(dw));
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_sf_viewport(const struct intel_cmd *cmd,
+                          enum intel_cmd_writer_type which,
+                          const struct intel_cmd_item *item)
+{
+    if (cmd_gen(cmd) >= INTEL_GEN(7))
+        writer_decode_sf_clip_viewport_gen7(cmd, which, item);
+    else
+        writer_decode_sf_viewport_gen6(cmd, which, item);
+}
+
+static void
+writer_decode_scissor_rect(const struct intel_cmd *cmd,
+                           enum intel_cmd_writer_type which,
+                           const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 2;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        uint32_t dw;
+
+        dw = writer_dw(cmd, which, offset, 0, "SCISSOR%d", i);
+        fprintf(stderr, "xmin %d, ymin %d\n",
+                READ(dw, GEN6_SCISSOR_DW0_MIN_X),
+                READ(dw, GEN6_SCISSOR_DW0_MIN_Y));
+
+        dw = writer_dw(cmd, which, offset, 1, "SCISSOR%d", i);
+        fprintf(stderr, "xmax %d, ymax %d\n",
+                READ(dw, GEN6_SCISSOR_DW1_MAX_X),
+                READ(dw, GEN6_SCISSOR_DW1_MAX_Y));
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_cc_viewport(const struct intel_cmd *cmd,
+                          enum intel_cmd_writer_type which,
+                          const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 2;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        uint32_t dw;
+
+        dw = writer_dw(cmd, which, offset, 0, "CC VP%d", i);
+        fprintf(stderr, "min_depth = %f\n", u_uif(dw));
+
+        dw = writer_dw(cmd, which, offset, 1, "CC VP%d", i);
+        fprintf(stderr, "max_depth = %f\n", u_uif(dw));
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_color_calc(const struct intel_cmd *cmd,
+                         enum intel_cmd_writer_type which,
+                         const struct intel_cmd_item *item)
+{
+    uint32_t dw;
+
+    dw = writer_dw(cmd, which, item->offset, 0, "CC");
+    fprintf(stderr, "alpha test format %s, round disable %d, "
+            "stencil ref %d, bf stencil ref %d\n",
+            READ(dw, GEN6_CC_DW0_ALPHATEST) ? "FLOAT32" : "UNORM8",
+            (bool) (dw & GEN6_CC_DW0_ROUND_DISABLE_DISABLE),
+            READ(dw, GEN6_CC_DW0_STENCIL0_REF),
+            READ(dw, GEN6_CC_DW0_STENCIL1_REF));
+
+    writer_dw(cmd, which, item->offset, 1, "CC\n");
+
+    dw = writer_dw(cmd, which, item->offset, 2, "CC");
+    fprintf(stderr, "constant red %f\n", u_uif(dw));
+
+    dw = writer_dw(cmd, which, item->offset, 3, "CC");
+    fprintf(stderr, "constant green %f\n", u_uif(dw));
+
+    dw = writer_dw(cmd, which, item->offset, 4, "CC");
+    fprintf(stderr, "constant blue %f\n", u_uif(dw));
+
+    dw = writer_dw(cmd, which, item->offset, 5, "CC");
+    fprintf(stderr, "constant alpha %f\n", u_uif(dw));
+}
+
+static void
+writer_decode_depth_stencil(const struct intel_cmd *cmd,
+                            enum intel_cmd_writer_type which,
+                            const struct intel_cmd_item *item)
+{
+    uint32_t dw;
+
+    dw = writer_dw(cmd, which, item->offset, 0, "D_S");
+    fprintf(stderr, "stencil %sable, func %d, write %sable\n",
+            (dw & GEN6_ZS_DW0_STENCIL_TEST_ENABLE) ? "en" : "dis",
+            READ(dw, GEN6_ZS_DW0_STENCIL0_FUNC),
+            (dw & GEN6_ZS_DW0_STENCIL_WRITE_ENABLE) ? "en" : "dis");
+
+    dw = writer_dw(cmd, which, item->offset, 1, "D_S");
+    fprintf(stderr, "stencil test mask 0x%x, write mask 0x%x\n",
+            READ(dw, GEN6_ZS_DW1_STENCIL0_VALUEMASK),
+            READ(dw, GEN6_ZS_DW1_STENCIL0_WRITEMASK));
+
+    dw = writer_dw(cmd, which, item->offset, 2, "D_S");
+    fprintf(stderr, "depth test %sable, func %d, write %sable\n",
+            (dw & GEN6_ZS_DW2_DEPTH_TEST_ENABLE) ? "en" : "dis",
+            READ(dw, GEN6_ZS_DW2_DEPTH_FUNC),
+            (dw & GEN6_ZS_DW2_DEPTH_WRITE_ENABLE) ? "en" : "dis");
+}
+
+static void
+writer_decode_blend(const struct intel_cmd *cmd,
+                    enum intel_cmd_writer_type which,
+                    const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 2;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        writer_dw(cmd, which, offset, 0, "BLEND%d\n", i);
+        writer_dw(cmd, which, offset, 1, "BLEND%d\n", i);
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_sampler(const struct intel_cmd *cmd,
+                      enum intel_cmd_writer_type which,
+                      const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 4;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        writer_dw(cmd, which, offset, 0, "WM SAMP%d", i);
+        fprintf(stderr, "filtering\n");
+
+        writer_dw(cmd, which, offset, 1, "WM SAMP%d", i);
+        fprintf(stderr, "wrapping, lod\n");
+
+        writer_dw(cmd, which, offset, 2, "WM SAMP%d", i);
+        fprintf(stderr, "default color pointer\n");
+
+        writer_dw(cmd, which, offset, 3, "WM SAMP%d", i);
+        fprintf(stderr, "chroma key, aniso\n");
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_surface_gen7(const struct intel_cmd *cmd,
+                           enum intel_cmd_writer_type which,
+                           const struct intel_cmd_item *item)
+{
+    uint32_t dw;
+
+    dw = writer_dw(cmd, which, item->offset, 0, "SURF");
+    fprintf(stderr, "type 0x%x, format 0x%x, tiling %d, %s array\n",
+            READ(dw, GEN7_SURFACE_DW0_TYPE),
+            READ(dw, GEN7_SURFACE_DW0_FORMAT),
+            READ(dw, GEN7_SURFACE_DW0_TILING),
+            (dw & GEN7_SURFACE_DW0_IS_ARRAY) ? "is" : "not");
+
+    writer_dw(cmd, which, item->offset, 1, "SURF");
+    fprintf(stderr, "offset\n");
+
+    dw = writer_dw(cmd, which, item->offset, 2, "SURF");
+    fprintf(stderr, "%dx%d size\n",
+            READ(dw, GEN7_SURFACE_DW2_WIDTH),
+            READ(dw, GEN7_SURFACE_DW2_HEIGHT));
+
+    dw = writer_dw(cmd, which, item->offset, 3, "SURF");
+    fprintf(stderr, "depth %d, pitch %d\n",
+            READ(dw, GEN7_SURFACE_DW3_DEPTH),
+            READ(dw, GEN7_SURFACE_DW3_PITCH));
+
+    dw = writer_dw(cmd, which, item->offset, 4, "SURF");
+    fprintf(stderr, "min array element %d, array extent %d\n",
+            READ(dw, GEN7_SURFACE_DW4_MIN_ARRAY_ELEMENT),
+            READ(dw, GEN7_SURFACE_DW4_RT_VIEW_EXTENT));
+
+    dw = writer_dw(cmd, which, item->offset, 5, "SURF");
+    fprintf(stderr, "mip base %d, mips %d, x,y offset: %d,%d\n",
+            READ(dw, GEN7_SURFACE_DW5_MIN_LOD),
+            READ(dw, GEN7_SURFACE_DW5_MIP_COUNT_LOD),
+            READ(dw, GEN7_SURFACE_DW5_X_OFFSET),
+            READ(dw, GEN7_SURFACE_DW5_Y_OFFSET));
+
+    writer_dw(cmd, which, item->offset, 6, "SURF\n");
+    writer_dw(cmd, which, item->offset, 7, "SURF\n");
+}
+
+static void
+writer_decode_surface_gen6(const struct intel_cmd *cmd,
+                           enum intel_cmd_writer_type which,
+                           const struct intel_cmd_item *item)
+{
+    uint32_t dw;
+
+    dw = writer_dw(cmd, which, item->offset, 0, "SURF");
+    fprintf(stderr, "type 0x%x, format 0x%x\n",
+            READ(dw, GEN6_SURFACE_DW0_TYPE),
+            READ(dw, GEN6_SURFACE_DW0_FORMAT));
+
+    writer_dw(cmd, which, item->offset, 1, "SURF");
+    fprintf(stderr, "offset\n");
+
+    dw = writer_dw(cmd, which, item->offset, 2, "SURF");
+    fprintf(stderr, "%dx%d size, %d mips\n",
+            READ(dw, GEN6_SURFACE_DW2_WIDTH),
+            READ(dw, GEN6_SURFACE_DW2_HEIGHT),
+            READ(dw, GEN6_SURFACE_DW2_MIP_COUNT_LOD));
+
+    dw = writer_dw(cmd, which, item->offset, 3, "SURF");
+    fprintf(stderr, "pitch %d, tiling %d\n",
+            READ(dw, GEN6_SURFACE_DW3_PITCH),
+            READ(dw, GEN6_SURFACE_DW3_TILING));
+
+    dw = writer_dw(cmd, which, item->offset, 4, "SURF");
+    fprintf(stderr, "mip base %d\n",
+            READ(dw, GEN6_SURFACE_DW4_MIN_LOD));
+
+    dw = writer_dw(cmd, which, item->offset, 5, "SURF");
+    fprintf(stderr, "x,y offset: %d,%d\n",
+            READ(dw, GEN6_SURFACE_DW5_X_OFFSET),
+            READ(dw, GEN6_SURFACE_DW5_Y_OFFSET));
+}
+
+static void
+writer_decode_surface(const struct intel_cmd *cmd,
+                      enum intel_cmd_writer_type which,
+                      const struct intel_cmd_item *item)
+{
+    if (cmd_gen(cmd) >= INTEL_GEN(7))
+        writer_decode_surface_gen7(cmd, which, item);
+    else
+        writer_decode_surface_gen6(cmd, which, item);
+}
+
+static void
+writer_decode_binding_table(const struct intel_cmd *cmd,
+                            enum intel_cmd_writer_type which,
+                            const struct intel_cmd_item *item)
+{
+    const unsigned state_size = sizeof(uint32_t) * 1;
+    const unsigned count = item->size / state_size;
+    unsigned offset = item->offset;
+    unsigned i;
+
+    for (i = 0; i < count; i++) {
+        writer_dw(cmd, which, offset, 0, "BIND");
+        fprintf(stderr, "BINDING_TABLE_STATE[%d]\n", i);
+
+        offset += state_size;
+    }
+}
+
+static void
+writer_decode_kernel(const struct intel_cmd *cmd,
+                     enum intel_cmd_writer_type which,
+                     const struct intel_cmd_item *item)
+{
+}
+
+static const struct {
+    void (*func)(const struct intel_cmd *cmd,
+                 enum intel_cmd_writer_type which,
+                 const struct intel_cmd_item *item);
+} writer_decode_table[INTEL_CMD_ITEM_COUNT] = {
+    [INTEL_CMD_ITEM_BLOB]                = { writer_decode_blob },
+    [INTEL_CMD_ITEM_CLIP_VIEWPORT]       = { writer_decode_clip_viewport },
+    [INTEL_CMD_ITEM_SF_VIEWPORT]         = { writer_decode_sf_viewport },
+    [INTEL_CMD_ITEM_SCISSOR_RECT]        = { writer_decode_scissor_rect },
+    [INTEL_CMD_ITEM_CC_VIEWPORT]         = { writer_decode_cc_viewport },
+    [INTEL_CMD_ITEM_COLOR_CALC]          = { writer_decode_color_calc },
+    [INTEL_CMD_ITEM_DEPTH_STENCIL]       = { writer_decode_depth_stencil },
+    [INTEL_CMD_ITEM_BLEND]               = { writer_decode_blend },
+    [INTEL_CMD_ITEM_SAMPLER]             = { writer_decode_sampler },
+    [INTEL_CMD_ITEM_SURFACE]             = { writer_decode_surface },
+    [INTEL_CMD_ITEM_BINDING_TABLE]       = { writer_decode_binding_table },
+    [INTEL_CMD_ITEM_KERNEL]              = { writer_decode_kernel },
+};
+
+static void cmd_writer_decode_items(struct intel_cmd *cmd,
+                                    enum intel_cmd_writer_type which)
+{
+    struct intel_cmd_writer *writer = &cmd->writers[which];
+    int i;
+
+    if (!writer->item_used)
+        return;
+
+    writer->ptr = intel_bo_map(writer->bo, false);
+    if (!writer->ptr)
+        return;
+
+    for (i = 0; i < writer->item_used; i++) {
+        const struct intel_cmd_item *item = &writer->items[i];
+
+        writer_decode_table[item->type].func(cmd, which, item);
+    }
+
+    intel_bo_unmap(writer->bo);
+}
+
+static void cmd_writer_decode(struct intel_cmd *cmd,
+                              enum intel_cmd_writer_type which)
+{
+    struct intel_cmd_writer *writer = &cmd->writers[which];
+
+    assert(writer->bo && !writer->ptr);
+
+    switch (which) {
+    case INTEL_CMD_WRITER_BATCH:
+        fprintf(stderr, "decoding batch buffer: %d bytes\n", writer->used);
+        if (writer->used) {
+            intel_winsys_decode_bo(cmd->dev->winsys,
+                    writer->bo, writer->used);
+        }
+        break;
+    case INTEL_CMD_WRITER_STATE:
+        fprintf(stderr, "decoding state buffer: %d states\n",
+                writer->item_used);
+        cmd_writer_decode_items(cmd, which);
+        break;
+    case INTEL_CMD_WRITER_INSTRUCTION:
+        if (true) {
+            fprintf(stderr, "skipping instruction buffer: %d kernels\n",
+                    writer->item_used);
+        } else {
+            fprintf(stderr, "decoding instruction buffer: %d kernels\n",
+                    writer->item_used);
+
+            cmd_writer_decode_items(cmd, which);
+        }
+        break;
+    default:
+        break;
+    }
+}
+
+/**
+ * Decode according to the recorded items.  This can be called only after a
+ * successful intel_cmd_end().
+ */
+void intel_cmd_decode(struct intel_cmd *cmd)
+{
+    int i;
+
+    assert(cmd->result == XGL_SUCCESS);
+
+    for (i = 0; i < INTEL_CMD_WRITER_COUNT; i++)
+        cmd_writer_decode(cmd, i);
+}