integration/export: Split _get_rw_functions_c in simpler functions.

litex/soc/integration/export.py

@@ -194,24 +194,30 @@ def get_soc_header(constants, with_access_functions=True):
     return r
 
 def _get_csr_addr(csr_base, addr, with_csr_base_define=True):
+    """
+    Generate the CSR address string.
+    """
     if with_csr_base_define:
         return f"(CSR_BASE + {hex(addr)}L)"
     else:
         return f"{hex(csr_base + addr)}L"
 
-def _get_rw_functions_c(reg_name, reg_base, nwords, busword, alignment, read_only, csr_base, with_csr_base_define, with_access_functions):
-    r = ""
-
+def _generate_csr_definitions_c(reg_name, reg_base, nwords, csr_base, with_csr_base_define):
+    """
+    Generate C code for CSR address and size definitions.
+    """
     addr_str    = f"CSR_{reg_name.upper()}_ADDR"
     size_str    = f"CSR_{reg_name.upper()}_SIZE"
-    r += f"#define {addr_str} {_get_csr_addr(csr_base, reg_base, with_csr_base_define)}\n"
+    definitions = f"#define {addr_str} {_get_csr_addr(csr_base, reg_base, with_csr_base_define)}\n"
+    definitions += f"#define {size_str} {nwords}\n"
+    return definitions
 
-    r += f"#define {size_str} {nwords}\n"
-
-    size = nwords*busword//8
+def _determine_ctype_and_stride_c(size, alignment):
+    """
+    Determine the C type and stride based on the size.
+    """
     if size > 8:
-        # Downstream should select appropriate `csr_[rd|wr]_buf_uintX()` pair!
-        return r
+        return None, None
     elif size > 4:
         ctype = "uint64_t"
     elif size > 2:
@@ -220,38 +226,61 @@ def _get_rw_functions_c(reg_name, reg_base, nwords, busword, alignment, read_onl
         ctype = "uint16_t"
     else:
         ctype = "uint8_t"
+    stride = alignment // 8
+    return ctype, stride
 
-    stride = alignment//8;
-    if with_access_functions:
-        r += f"static inline {ctype} {reg_name}_read(void) {{\n"
+def _generate_read_function_c(reg_name, reg_base, nwords, busword, ctype, stride, csr_base, with_csr_base_define):
+    """
+    Generate C code for the read function of a CSR.
+    """
+    read_function = f"static inline {ctype} {reg_name}_read(void) {{\n"
     if nwords > 1:
-            r += f"\t{ctype} r = csr_read_simple({_get_csr_addr(csr_base, reg_base, with_csr_base_define)});\n"
+        read_function += f"\t{ctype} r = csr_read_simple({_get_csr_addr(csr_base, reg_base, with_csr_base_define)});\n"
         for sub in range(1, nwords):
-                r += f"\tr <<= {busword};\n"
-                r += f"\tr |= csr_read_simple({_get_csr_addr(csr_base, reg_base+sub*stride, with_csr_base_define)});\n"
-            r += "\treturn r;\n}\n"
+            read_function += f"\tr <<= {busword};\n"
+            read_function += f"\tr |= csr_read_simple({_get_csr_addr(csr_base, reg_base + sub * stride, with_csr_base_define)});\n"
+        read_function += "\treturn r;\n}}\n"
     else:
-            r += f"\treturn csr_read_simple({_get_csr_addr(csr_base, reg_base, with_csr_base_define)});\n}}\n"
+        read_function += f"\treturn csr_read_simple({_get_csr_addr(csr_base, reg_base, with_csr_base_define)});\n}}\n"
+    return read_function
 
-        if not read_only:
-            r += f"static inline void {reg_name}_write({ctype} v) {{\n"
+def _generate_write_function_c(reg_name, reg_base, nwords, busword, ctype, stride, csr_base, with_csr_base_define):
+    """
+    Generate C code for the write function of a CSR.
+    """
+    write_function = f"static inline void {reg_name}_write({ctype} v) {{\n"
     for sub in range(nwords):
         shift = (nwords - sub - 1) * busword
-                if shift:
-                    v_shift = "v >> {}".format(shift)
-                else:
-                    v_shift = "v"
-                r += f"\tcsr_write_simple({v_shift}, {_get_csr_addr(csr_base, reg_base+sub*stride, with_csr_base_define)});\n"
-            r += "}\n"
-    return r
+        v_shift = f"v >> {shift}" if shift else "v"
+        write_function += f"\tcsr_write_simple({v_shift}, {_get_csr_addr(csr_base, reg_base + sub * stride, with_csr_base_define)});\n"
+    write_function += "}\n"
+    return write_function
 
+def _get_rw_functions_c(reg_name, reg_base, nwords, busword, alignment, read_only, csr_base, with_csr_base_define, with_access_functions):
+    """
+    Generate C code for CSR read/write functions and definitions.
+    """
+    result = _generate_csr_definitions_c(reg_name, reg_base, nwords, csr_base, with_csr_base_define)
+    size = nwords * busword // 8
+
+    ctype, stride = _determine_ctype_and_stride_c(size, alignment)
+    if ctype is None:
+        return result
+
+    if with_access_functions:
+        result += _generate_read_function_c(reg_name, reg_base, nwords, busword, ctype, stride, csr_base, with_csr_base_define)
+        if not read_only:
+            result += _generate_write_function_c(reg_name, reg_base, nwords, busword, ctype, stride, csr_base, with_csr_base_define)
+
+    return result
 
 def get_csr_header(regions, constants, csr_base=None, with_csr_base_define=True, with_access_functions=True):
     alignment = constants.get("CONFIG_CSR_ALIGNMENT", 32)
     r = generated_banner("//")
     if with_access_functions: # FIXME
         r += "#include <generated/soc.h>\n"
-    r += "#ifndef __GENERATED_CSR_H\n#define __GENERATED_CSR_H\n"
+    r += "#ifndef __GENERATED_CSR_H\n"
+    r += "#define __GENERATED_CSR_H\n"
     if with_access_functions:
         r += "#include <stdint.h>\n"
         r += "#include <system.h>\n"