feat(lib): add a generic EXTRACT macro
The EXTRACT macro is useful to extract a named field from a numeric
value, usually a register. It is functionally identical to the `ubfx`
instruction and uses the same #defines (REG_FIELD_SHIFT and
REG_FIELD_WIDTH).
This is the same macro that we use in tftf. It works well there and is
quite useful for manipulating register fields concisely.
This macro replaces the EXTRACT_FIELD macro. Their function is
identical, however, EXTRACT allows for easier interoperation with the
`ubfx` instruction, makes code more similar to tftf, and is more
concise.
Change-Id: Ic454a87af5e5fac108c7b7cb6b6804ec65a8d0e8
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
diff --git a/include/lib/utils_def.h b/include/lib/utils_def.h
index 098506a..68e464a 100644
--- a/include/lib/utils_def.h
+++ b/include/lib/utils_def.h
@@ -58,12 +58,34 @@
#define GENMASK GENMASK_32
#endif
+/*
+ * Similar to GENMASK_64 but uses a named register field to compute the mask.
+ * For a register field REG_FIELD, the macros REG_FIELD_WIDTH and
+ * REG_FIELD_SHIFT must be defined.
+ */
+#define MASK(regfield) \
+ ((~0ULL >> (64ULL - (regfield##_WIDTH))) << (regfield##_SHIFT))
+
#define HI(addr) (addr >> 32)
#define LO(addr) (addr & 0xffffffff)
#define HI_64(addr) (addr >> 64)
#define LO_64(addr) (addr & 0xffffffffffffffff)
+/**
+ * EXTRACT_FIELD - Extracts a specific bit field from a value.
+ *
+ * @reg: The input value containing the field.
+
+ * @regfield: A bitmask representing the field. For a register field REG_FIELD,
+ * the macros REG_FIELD_WIDTH and REG_FIELD_SHIFT must be defined.
+
+ * The result of this macro is the contents of the field right shifted to the
+ * least significant bit positions, with the rest being zero.
+ */
+#define EXTRACT(regfield, reg) \
+ (((reg) & MASK(regfield)) >> (regfield##_SHIFT))
+
/*
* This variant of div_round_up can be used in macro definition but should not
* be used in C code as the `div` parameter is evaluated twice.
@@ -221,17 +243,4 @@
*/
#define KHZ_TICKS_PER_SEC U(1000)
-/**
- * EXTRACT_FIELD - Extracts a specific bit field from a value.
- *
- * @val: The input value containing the field.
- * @mask: A bitmask representing the maximum value of the field
- * @shift: The starting bit position of the field.
- *
- * This macro shifts the input value (@val) to the right by @shift bits,
- * aligning the target field to the least significant bits (LSB).
- * It then applies @mask to extract only the relevant bits.
- */
-#define EXTRACT_FIELD(val, mask, shift) (((val) >> (shift)) & (mask))
-
#endif /* UTILS_DEF_H */