On 1/9/22 07:32, Richard Henderson wrote:
On 9/1/22 02:02, Wilfred Mallawa wrote:
From: Wilfred Mallawa <wilfred.mall...@wdc.com>
Adds a helper macro that implements the `rw1c`
behaviour.
Ex:
uint32_t data = FIELD32_1CLEAR(val, REG, FIELD);
if the specified `FIELD` is set (single/multi bit all fields)
then the respective field is cleared and returned to `data`.
If ALL bits of the bitfield are not set, then no change and
val is returned.
Signed-off-by: Wilfred Mallawa <wilfred.mall...@wdc.com>
Why do these operations need to go into hw/registerfields.h?
It's not a common operation, since we've never needed it so far.
I suggested it to improve readability of this patch:
https://lore.kernel.org/qemu-devel/c33257a3-645f-9386-52e5-21a15ef0e...@amsat.org/
---
include/hw/registerfields.h | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/include/hw/registerfields.h b/include/hw/registerfields.h
index 1330ca77de..5a804f72e3 100644
--- a/include/hw/registerfields.h
+++ b/include/hw/registerfields.h
@@ -115,6 +115,34 @@
R_ ## reg ## _ ## field ## _LENGTH,
_v.v); \
_d; })
+/* Get the max value (uint) discribed by `num_bits` bits */
+#define MAX_N_BITS(num_bits) ((1 << (num_bits)) - 1)
+
+/*
+ * Clear the specified field in reg_val if
+ * all field bits are set, else no changes made. Implements
+ * single/multi-bit `rw1c`
+ */
+#define FIELD8_1CLEAR(reg_val, reg,
field) \
+ ((FIELD_EX8(reg_val, reg, field)
== \
+ MAX_N_BITS(R_ ## reg ## _ ## field ## _LENGTH))
? \
+ FIELD_DP8(reg_val, reg, field, 0x00) : reg_val)
+
+#define FIELD16_1CLEAR(reg_val, reg,
field) \
+ ((FIELD_EX16(reg_val, reg, field)
== \
+ MAX_N_BITS(R_ ## reg ## _ ## field ## _LENGTH))
? \
+ FIELD_DP16(reg_val, reg, field, 0x00) : reg_val)
+
+#define FIELD32_1CLEAR(reg_val, reg,
field) \
+ ((FIELD_EX32(reg_val, reg, field)
== \
+ MAX_N_BITS(R_ ## reg ## _ ## field ## _LENGTH))
? \
+ FIELD_DP32(reg_val, reg, field, 0x00) : reg_val)
+
+#define FIELD64_1CLEAR(reg_val, reg,
field) \
+ ((FIELD_EX64(reg_val, reg, field)
== \
+ MAX_N_BITS(R_ ## reg ## _ ## field ## _LENGTH))
? \
+ FIELD_DP64(reg_val, reg, field, 0x00) : reg_val)
+
#define FIELD_SDP8(storage, reg, field, val)
({ \
struct
{ \
signed int v:R_ ## reg ## _ ## field ##
_LENGTH; \
