// TODO: CHECK/REPLACE/UPDATE OLD CODE (this file is based on xv6)
#ifndef __ASSEMBLER__
/* This file was originally filled with inline assembly routines but
 * they have been moved to functions in riscv.S to ease porting between
 * compilers (the alternative would be to have #ifdefs for different
 * inline asm syntaxes).
 */

// which hart (core) is this?
uint64 r_mhartid();

// Machine Status Register, mstatus

#define MSTATUS_MPP_MASK (3L << 11) // previous mode.
#define MSTATUS_MPP_M (3L << 11)
#define MSTATUS_MPP_S (1L << 11)
#define MSTATUS_MPP_U (0L << 11)
#define MSTATUS_MIE (1L << 3)    // machine-mode interrupt enable.

uint64 r_mstatus();

void w_mstatus(uint64 x);

// machine exception program counter, holds the
// instruction address to which a return from
// exception will go.
void w_mepc(uint64 x);

// Supervisor Status Register, sstatus

#define SSTATUS_SPP (1L << 8)  // Previous mode, 1=Supervisor, 0=User
#define SSTATUS_SPIE (1L << 5) // Supervisor Previous Interrupt Enable
#define SSTATUS_UPIE (1L << 4) // User Previous Interrupt Enable
#define SSTATUS_SIE (1L << 1)  // Supervisor Interrupt Enable
#define SSTATUS_UIE (1L << 0)  // User Interrupt Enable

uint64 r_sstatus();

void w_sstatus(uint64 x);

// Supervisor Interrupt Pending
uint64 r_sip();

void w_sip(uint64 x);

// Supervisor Interrupt Enable
#define SIE_SEIE (1L << 9) // external
#define SIE_STIE (1L << 5) // timer
#define SIE_SSIE (1L << 1) // software
uint64 r_sie();

void w_sie(uint64 x);

// Machine-mode Interrupt Enable
#define MIE_STIE (1L << 5)  // supervisor timer
uint64 r_mie();

void w_mie(uint64 x);

// supervisor exception program counter, holds the
// instruction address to which a return from
// exception will go.
void w_sepc(uint64 x);

uint64 r_sepc();

// Machine Exception Delegation
uint64 r_medeleg();

void w_medeleg(uint64 x);

// Machine Interrupt Delegation
uint64 r_mideleg();

void w_mideleg(uint64 x);

// Supervisor Trap-Vector Base Address
// low two bits are mode.
void w_stvec(uint64 x);

uint64 r_stvec();

// Supervisor Timer Comparison Register
uint64 r_stimecmp();

void w_stimecmp(uint64 x);

// Machine Environment Configuration Register
uint64 r_menvcfg();

void w_menvcfg(uint64 x);

// Physical Memory Protection
void w_pmpcfg0(uint64 x);

void w_pmpaddr0(uint64 x);

// use riscv's sv39 page table scheme.
#define SATP_SV39 (8L << 60)

#define MAKE_SATP(pagetable) (SATP_SV39 | (((uint64)(pagetable)) >> 12))

// supervisor address translation and protection;
// holds the address of the page table.
void w_satp(uint64 x);

uint64 r_satp();

// Supervisor Trap Cause
uint64 r_scause();

// Supervisor Trap Value
uint64 r_stval();

// Machine-mode Counter-Enable
void w_mcounteren(uint64 x);

uint64 r_mcounteren();

// machine-mode cycle counter
uint64 r_time();

/* These should really be moved back into C but were included in the .s
 * for consistency.
 * 
// enable device interrupts
void
intr_on()
{
  w_sstatus(r_sstatus() | SSTATUS_SIE);
}

// disable device interrupts
void
intr_off()
{
  w_sstatus(r_sstatus() & ~SSTATUS_SIE);
}

// are device interrupts enabled?
int
intr_get()
{
  uint64 x = r_sstatus();
  return (x & SSTATUS_SIE) != 0;
}
*/

// enable device interrupts
void intr_on();

// disable device interrupts
void intr_off();

// are device interrupts enabled?
int intr_get();

uint64 r_sp();

// read and write tp, the thread pointer, which xv6 uses to hold
// this core's hartid (core number), the index into cpus[].
//uint64 r_tp();

void w_tp(uint64 x);

uint64 r_ra();

// flush the TLB.
void sfence_vma();

typedef uint64 pte_t;
typedef uint64 *pagetable_t; // 512 PTEs

#endif // __ASSEMBLER__

#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) // user can access

// shift a physical address to the right place for a PTE.
#define PA2PTE(pa) ((((uint64)pa) >> 12) << 10)

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

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

// extract the three 9-bit page table indices from a virtual address.
#define PXMASK          0x1FF // 9 bits
#define PXSHIFT(level)  (PGSHIFT+(9*(level)))
#define PX(level, va) ((((uint64) (va)) >> PXSHIFT(level)) & PXMASK)

// one beyond the highest possible virtual address.
// MAXVA is actually one bit less than the max allowed by
// Sv39, to avoid having to sign-extend virtual addresses
// that have the high bit set.
#define MAXVA (1L << (9 + 9 + 9 + 12 - 1))