Add RISC-V CMO extension's intrinsics

Author: Liaoshihua

src/c-api.adoc

@@ -485,6 +485,48 @@ RISC-V intrinsics examples:
 vint8m1_t __riscv_vadd_vv_i8m1(vint8m1_t vs2, vint8m1_t vs1, size_t vl); // vadd.vv vd, vs2, vs1
 ----
 
+=== CMO Intrinsics
+
+The RISC-V CMO extension provides instruction for perform operations on copies 
+of data in the memory hierarchy.
+
+In order to access the RISC-V CMO intrinsics, it is necessary to
+include the header file `riscv_cmo.h`.
+
+The functions are only available if the compiler's `-march` string enables the
+required ISA extension.
+
+.CMO Extension Intrinsics
+[%autowidth]
+|===
+|*Prototype*                                                                              |*Instruction*        |*Extension*    |*Notes*
+|`+void __riscv_cmo_clean(void *addr);+`                                                  |`cbo.clean`          |Zicbom         |
+|`+void __riscv_cmo_flush(void *addr);+`                                                  |`cbo.flush`          |Zicbom         |
+|`+void __riscv_cmo_inval(void *addr);+`                                                  |`cbo.inval`          |Zicbom         |
+|`+void __riscv_cmo_zero(void *addr);+`                                                   |`cbo.zero`           |Zicboz         |
+|`+void __riscv_cmo_prefetch(void *addr, const int rw, const int locality);+`             |`prefetch.[r][w]`    |Zicbop         | `rw`= [0,1], `locality` = [0..3].
+|`+int  __riscv_cmo_prefetchi(const int locality);+`                                      |`prefetch.i`         |Zicbop         |
+|===
+
+Note: riscv_cmo_prefetch is a wrapper around builtin_prefetch.
+Similar to Prefetch Intrinsics, the following table presents the mapping from
+the riscv_cmo_prefetch function to the corresponding assembly instructions,
+assuming the presence of the Zihintntl and Zicbop extensions.
+
+.CMO Functions to Assembly Mapping with Zihintntl
+[%autowidth]
+|===
+|*Prefetch function*                                 |*Assembly*
+|`+__riscv_cmo_prefetch(ptr, 0, 0 /* locality */);+` |`ntl.all + prefetch.r (ptr)`
+|`+__riscv_cmo_prefetch(ptr, 0, 1 /* locality */);+` |`ntl.pall + prefetch.r (ptr)`
+|`+__riscv_cmo_prefetch(ptr, 0, 2 /* locality */);+` |`ntl.p1 + prefetch.r (ptr)`
+|`+__riscv_cmo_prefetch(ptr, 0, 3 /* locality */);+` |`prefetch.r (ptr)`
+|`+__riscv_cmo_prefetch(ptr, 1, 0 /* locality */);+` |`ntl.all + prefetch.w (ptr)`
+|`+__riscv_cmo_prefetch(ptr, 1, 1 /* locality */);+` |`ntl.pall + prefetch.w (ptr)`
+|`+__riscv_cmo_prefetch(ptr, 1, 2 /* locality */);+` |`ntl.p1 + prefetch.w (ptr)`
+|`+__riscv_cmo_prefetch(ptr, 1, 3 /* locality */);+` |`prefetch.w (ptr)`
+|===
+
 === NTLH Intrinsics