// Copyright 2022 hrpccs
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

typedef unsigned int uint32;
typedef uint32 pte_t;
typedef uint32* pagetable_t;

#define PGSIZE 4096 // bytes per page
#define PGSHIFT 12  // bits of offset within a page

#define PGROUNDUP(sz)  (((sz)+PGSIZE-1) & ~(PGSIZE-1))
#define PGROUNDDOWN(a) (((a)) & ~(PGSIZE-1))

#define PTE_V (1L << 0) // valid
#define PTE_R (1L << 1)
#define PTE_W (1L << 2)
#define PTE_X (1L << 3)
#define PTE_U (1L << 4) // 1 -> user can access

// shift a physical address to the right place for a PTE.
#define PA2PTE(pa) ((((uint32)pa) >> 12) << 10)

#define PTE2PA(pte) (((pte) >> 10) << 12)

#define PTE_FLAGS(pte) ((pte) & 0x3FF)

// extract the two 10-bit page table indices from a virtual address.
#define PXMASK          0x3FF // 10 bits
#define PXSHIFT(level)  (PGSHIFT+(10*(level)))
#define PX(level, va) ((((uint32) (va)) >> PXSHIFT(level)) & PXMASK)

#define MAXVA (1L << (10 + 10 + 12))