[PATCH 06/26] hw/intc/arm_gicv3_its: Reduce code duplication in extract_table_params()

[Peter Maydell]

The extract_table_params() decodes the fields in the GITS_BASER<n>
registers into TableDesc structs.  Since the fields are the same for
all the GITS_BASER<n> registers, there is currently a lot of code
duplication within the switch (type) statement.  Refactor so that the
cases include only what is genuinely different for each type:
the calculation of the number of bits in the ID value that indexes
into the table.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/intc/arm_gicv3_its.c | 97 +++++++++++++++++------------------------
 1 file changed, 40 insertions(+), 57 deletions(-)

diff --git a/hw/intc/arm_gicv3_its.c b/hw/intc/arm_gicv3_its.c
index c97b9982ae1..84808b1e298 100644
--- a/hw/intc/arm_gicv3_its.c
+++ b/hw/intc/arm_gicv3_its.c
@@ -758,6 +758,9 @@ static void extract_table_params(GICv3ITSState *s)
     uint64_t value;
 
     for (int i = 0; i < 8; i++) {
+        TableDesc *td;
+        int idbits;
+
         value = s->baser[i];
 
         if (!value) {
@@ -789,73 +792,53 @@ static void extract_table_params(GICv3ITSState *s)
         type = FIELD_EX64(value, GITS_BASER, TYPE);
 
         switch (type) {
-
         case GITS_BASER_TYPE_DEVICE:
-            memset(&s->dt, 0 , sizeof(s->dt));
-            s->dt.valid = FIELD_EX64(value, GITS_BASER, VALID);
-
-            if (!s->dt.valid) {
-                break;
-            }
-
-            s->dt.page_sz = page_sz;
-            s->dt.indirect = FIELD_EX64(value, GITS_BASER, INDIRECT);
-            s->dt.entry_sz = FIELD_EX64(value, GITS_BASER, ENTRYSIZE);
-
-            if (!s->dt.indirect) {
-                s->dt.max_entries = (num_pages * page_sz) / s->dt.entry_sz;
-            } else {
-                s->dt.max_entries = (((num_pages * page_sz) /
-                                     L1TABLE_ENTRY_SIZE) *
-                                     (page_sz / s->dt.entry_sz));
-            }
-
-            s->dt.max_ids = (1UL << (FIELD_EX64(s->typer, GITS_TYPER,
-                                                DEVBITS) + 1));
-
-            s->dt.base_addr = baser_base_addr(value, page_sz);
-
+            td = &s->dt;
+            idbits = FIELD_EX64(s->typer, GITS_TYPER, DEVBITS) + 1;
             break;
-
         case GITS_BASER_TYPE_COLLECTION:
-            memset(&s->ct, 0 , sizeof(s->ct));
-            s->ct.valid = FIELD_EX64(value, GITS_BASER, VALID);
-
-            /*
-             * GITS_TYPER.HCC is 0 for this implementation
-             * hence writes are discarded if ct.valid is 0
-             */
-            if (!s->ct.valid) {
-                break;
-            }
-
-            s->ct.page_sz = page_sz;
-            s->ct.indirect = FIELD_EX64(value, GITS_BASER, INDIRECT);
-            s->ct.entry_sz = FIELD_EX64(value, GITS_BASER, ENTRYSIZE);
-
-            if (!s->ct.indirect) {
-                s->ct.max_entries = (num_pages * page_sz) / s->ct.entry_sz;
-            } else {
-                s->ct.max_entries = (((num_pages * page_sz) /
-                                     L1TABLE_ENTRY_SIZE) *
-                                     (page_sz / s->ct.entry_sz));
-            }
-
+            td = &s->ct;
             if (FIELD_EX64(s->typer, GITS_TYPER, CIL)) {
-                s->ct.max_ids = (1UL << (FIELD_EX64(s->typer,
-                                                    GITS_TYPER, CIDBITS) + 1));
+                idbits = FIELD_EX64(s->typer, GITS_TYPER, CIDBITS) + 1;
             } else {
                 /* 16-bit CollectionId supported when CIL == 0 */
-                s->ct.max_ids = (1UL << 16);
+                idbits = 16;
             }
-
-            s->ct.base_addr = baser_base_addr(value, page_sz);
-
             break;
-
         default:
-            break;
+            /*
+             * GITS_BASER<n>.TYPE is read-only, so GITS_BASER_RO_MASK
+             * ensures we will only see type values corresponding to
+             * the values set up in gicv3_its_reset().
+             */
+            g_assert_not_reached();
         }
+
+        memset(td, 0, sizeof(*td));
+        td->valid = FIELD_EX64(value, GITS_BASER, VALID);
+        /*
+         * If GITS_BASER<n>.Valid is 0 for any <n> then we will not process
+         * interrupts. (GITS_TYPER.HCC is 0 for this implementation, so we
+         * do not have a special case where the GITS_BASER<n>.Valid bit is 0
+         * for the register corresponding to the Collection table but we
+         * still have to process interrupts using non-memory-backed
+         * Collection table entries.)
+         */
+        if (!td->valid) {
+            continue;
+        }
+        td->page_sz = page_sz;
+        td->indirect = FIELD_EX64(value, GITS_BASER, INDIRECT);
+        td->entry_sz = FIELD_EX64(value, GITS_BASER, ENTRYSIZE);
+        td->base_addr = baser_base_addr(value, page_sz);
+        if (!td->indirect) {
+            td->max_entries = (num_pages * page_sz) / td->entry_sz;
+        } else {
+            td->max_entries = (((num_pages * page_sz) /
+                                  L1TABLE_ENTRY_SIZE) *
+                                 (page_sz / td->entry_sz));
+        }
+        td->max_ids = 1ULL << idbits;
     }
 }
 
-- 
2.25.1