diff --git a/.gitignore b/.gitignore
index 2f31ace..84c3ed2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,3 +16,4 @@ _*
 *~
 build/
 !.gitignore
+.vscode
\ No newline at end of file
diff --git a/am/include/arch/riscv64-mycpu.h b/am/include/arch/riscv64-mycpu.h
new file mode 100644
index 0000000..5c75646
--- /dev/null
+++ b/am/include/arch/riscv64-mycpu.h
@@ -0,0 +1,16 @@
+#ifndef ARCH_H__
+#define ARCH_H__
+
+struct Context {
+  // TODO: fix the order of these members to match trap.S
+  uintptr_t epc, cause, gpr[32], status;
+};
+
+#define GPR1 gpr[0]
+#define GPR2 gpr[0]
+#define GPR3 gpr[0]
+#define GPR4 gpr[0]
+#define GPRx gpr[0]
+
+#endif
+
diff --git a/am/src/mycpu/cte.c b/am/src/mycpu/cte.c
new file mode 100644
index 0000000..b94083f
--- /dev/null
+++ b/am/src/mycpu/cte.c
@@ -0,0 +1,45 @@
+#include <am.h>
+#include <klib.h>
+
+static Context* (*user_handler)(Event, Context*) = NULL;
+
+Context* __am_irq_handle(Context *c) {
+  if (user_handler) {
+    Event ev = {0};
+    switch (c->cause) {
+      default: ev.event = EVENT_ERROR; break;
+    }
+
+    c = user_handler(ev, c);
+    assert(c != NULL);
+  }
+
+  return c;
+}
+
+extern void __am_asm_trap(void);
+
+bool cte_init(Context*(*handler)(Event, Context*)) {
+  // initialize exception entry
+  asm volatile("csrw mtvec, %0" : : "r"(__am_asm_trap));
+
+  // register event handler
+  user_handler = handler;
+
+  return true;
+}
+
+Context *kcontext(Area kstack, void (*entry)(void *), void *arg) {
+  return NULL;
+}
+
+void yield() {
+  asm volatile("li a7, -1; ecall");
+}
+
+bool ienabled() {
+  return false;
+}
+
+void iset(bool enable) {
+}
diff --git a/am/src/mycpu/input.c b/am/src/mycpu/input.c
new file mode 100644
index 0000000..0460fa4
--- /dev/null
+++ b/am/src/mycpu/input.c
@@ -0,0 +1,6 @@
+#include <am.h>
+
+void __am_input_keybrd(AM_INPUT_KEYBRD_T *kbd) {
+  kbd->keydown = 0;
+  kbd->keycode = AM_KEY_NONE;
+}
diff --git a/am/src/mycpu/ioe.c b/am/src/mycpu/ioe.c
new file mode 100644
index 0000000..97a306d
--- /dev/null
+++ b/am/src/mycpu/ioe.c
@@ -0,0 +1,33 @@
+#include <am.h>
+#include <klib-macros.h>
+
+void __am_timer_init();
+
+void __am_timer_rtc(AM_TIMER_RTC_T *);
+void __am_timer_uptime(AM_TIMER_UPTIME_T *);
+void __am_input_keybrd(AM_INPUT_KEYBRD_T *);
+void __am_timer_rtc(AM_TIMER_RTC_T *);
+
+static void __am_timer_config(AM_TIMER_CONFIG_T *cfg) { cfg->present = true; cfg->has_rtc = true; }
+static void __am_input_config(AM_INPUT_CONFIG_T *cfg) { cfg->present = true;  }
+
+typedef void (*handler_t)(void *buf);
+static void *lut[128] = {
+  [AM_TIMER_CONFIG] = __am_timer_config,
+  [AM_TIMER_RTC   ] = __am_timer_rtc,
+  [AM_TIMER_UPTIME] = __am_timer_uptime,
+  [AM_INPUT_CONFIG] = __am_input_config,
+  [AM_INPUT_KEYBRD] = __am_input_keybrd,
+};
+
+static void fail(void *buf) { panic("access nonexist register"); }
+
+bool ioe_init() {
+  for (int i = 0; i < LENGTH(lut); i++)
+    if (!lut[i]) lut[i] = fail;
+  __am_timer_init();
+  return true;
+}
+
+void ioe_read (int reg, void *buf) { ((handler_t)lut[reg])(buf); }
+void ioe_write(int reg, void *buf) { ((handler_t)lut[reg])(buf); }
diff --git a/am/src/mycpu/libgcc/div.S b/am/src/mycpu/libgcc/div.S
new file mode 100644
index 0000000..0d394d2
--- /dev/null
+++ b/am/src/mycpu/libgcc/div.S
@@ -0,0 +1,140 @@
+#define FUNC_TYPE(X)	.type X,@function
+#define FUNC_SIZE(X)	.size X,.-X
+
+#define FUNC_BEGIN(X)		\
+	.globl X;		\
+	FUNC_TYPE (X);		\
+X:
+
+#define FUNC_END(X)		\
+	FUNC_SIZE(X)
+
+#define FUNC_ALIAS(X,Y)		\
+	.globl X;		\
+	X = Y
+
+
+#define __riscv_xlen 64
+
+  .text
+  .align 2
+
+#if __riscv_xlen == 32
+/* Our RV64 64-bit routines are equivalent to our RV32 32-bit routines.  */
+# define __udivdi3 __udivsi3
+# define __umoddi3 __umodsi3
+# define __divdi3 __divsi3
+# define __moddi3 __modsi3
+#else
+FUNC_BEGIN (__udivsi3)
+  /* Compute __udivdi3(a0 << 32, a1 << 32); cast result to uint32_t.  */
+  sll    a0, a0, 32
+  sll    a1, a1, 32
+  move   t0, ra
+  jal    __udivdi3
+  sext.w a0, a0
+  jr     t0
+FUNC_END (__udivsi3)
+
+FUNC_BEGIN (__umodsi3)
+  /* Compute __udivdi3((uint32_t)a0, (uint32_t)a1); cast a1 to uint32_t.  */
+  sll    a0, a0, 32
+  sll    a1, a1, 32
+  srl    a0, a0, 32
+  srl    a1, a1, 32
+  move   t0, ra
+  jal    __udivdi3
+  sext.w a0, a1
+  jr     t0
+FUNC_END (__umodsi3)
+
+FUNC_ALIAS (__modsi3, __moddi3)
+
+FUNC_BEGIN( __divsi3)
+  /* Check for special case of INT_MIN/-1. Otherwise, fall into __divdi3.  */
+  li    t0, -1
+  beq   a1, t0, .L20
+#endif
+
+FUNC_BEGIN (__divdi3)
+  bltz  a0, .L10
+  bltz  a1, .L11
+  /* Since the quotient is positive, fall into __udivdi3.  */
+
+FUNC_BEGIN (__udivdi3)
+  mv    a2, a1
+  mv    a1, a0
+  li    a0, -1
+  beqz  a2, .L5
+  li    a3, 1
+  bgeu  a2, a1, .L2
+.L1:
+  blez  a2, .L2
+  slli  a2, a2, 1
+  slli  a3, a3, 1
+  bgtu  a1, a2, .L1
+.L2:
+  li    a0, 0
+.L3:
+  bltu  a1, a2, .L4
+  sub   a1, a1, a2
+  or    a0, a0, a3
+.L4:
+  srli  a3, a3, 1
+  srli  a2, a2, 1
+  bnez  a3, .L3
+.L5:
+  ret
+FUNC_END (__udivdi3)
+
+FUNC_BEGIN (__umoddi3)
+  /* Call __udivdi3(a0, a1), then return the remainder, which is in a1.  */
+  move  t0, ra
+  jal   __udivdi3
+  move  a0, a1
+  jr    t0
+FUNC_END (__umoddi3)
+
+  /* Handle negative arguments to __divdi3.  */
+.L10:
+  neg   a0, a0
+  /* Zero is handled as a negative so that the result will not be inverted.  */
+  bgtz  a1, .L12     /* Compute __udivdi3(-a0, a1), then negate the result.  */
+
+  neg   a1, a1
+  j     __udivdi3    /* Compute __udivdi3(-a0, -a1).  */
+.L11:                /* Compute __udivdi3(a0, -a1), then negate the result.  */
+  neg   a1, a1
+.L12:
+  move  t0, ra
+  jal   __udivdi3
+  neg   a0, a0
+  jr    t0
+FUNC_END (__divdi3)
+
+FUNC_BEGIN (__moddi3)
+  move   t0, ra
+  bltz   a1, .L31
+  bltz   a0, .L32
+.L30:
+  jal    __udivdi3    /* The dividend is not negative.  */
+  move   a0, a1
+  jr     t0
+.L31:
+  neg    a1, a1
+  bgez   a0, .L30
+.L32:
+  neg    a0, a0
+  jal    __udivdi3    /* The dividend is hella negative.  */
+  neg    a0, a1
+  jr     t0
+FUNC_END (__moddi3)
+
+#if __riscv_xlen == 64
+  /* continuation of __divsi3 */
+.L20:
+  sll   t0, t0, 31
+  bne   a0, t0, __divdi3
+  ret
+FUNC_END (__divsi3)
+#endif
diff --git a/am/src/mycpu/libgcc/muldi3.S b/am/src/mycpu/libgcc/muldi3.S
new file mode 100644
index 0000000..c9e131d
--- /dev/null
+++ b/am/src/mycpu/libgcc/muldi3.S
@@ -0,0 +1,25 @@
+#define FUNC_TYPE(X)	.type X,@function
+#define FUNC_SIZE(X)	.size X,.-X
+
+#define FUNC_BEGIN(X)		\
+	.globl X;		\
+	FUNC_TYPE (X);		\
+X:
+
+#define FUNC_END(X)		\
+	FUNC_SIZE(X)
+
+
+FUNC_BEGIN (__muldi3)
+  mv     a2, a0
+  li     a0, 0
+.L1:
+  andi   a3, a1, 1
+  beqz   a3, .L2
+  add    a0, a0, a2
+.L2:
+  srli   a1, a1, 1
+  slli   a2, a2, 1
+  bnez   a1, .L1
+  ret
+FUNC_END (__muldi3)
\ No newline at end of file
diff --git a/am/src/mycpu/mpe.c b/am/src/mycpu/mpe.c
new file mode 100644
index 0000000..6715aa2
--- /dev/null
+++ b/am/src/mycpu/mpe.c
@@ -0,0 +1,17 @@
+#include <am.h>
+
+bool mpe_init(void (*entry)()) {
+  return false;
+}
+
+int cpu_count() {
+  return 1;
+}
+
+int cpu_current() {
+  return 0;
+}
+
+int atomic_xchg(int *addr, int newval) {
+  return 0;
+}
diff --git a/am/src/mycpu/start.S b/am/src/mycpu/start.S
new file mode 100644
index 0000000..3e56e5c
--- /dev/null
+++ b/am/src/mycpu/start.S
@@ -0,0 +1,8 @@
+.section entry, "ax"
+.globl _start
+.type _start, @function
+
+_start:
+  mv s0, zero
+  la sp, _stack_pointer
+  jal _trm_init
diff --git a/am/src/mycpu/timer.c b/am/src/mycpu/timer.c
new file mode 100644
index 0000000..6ea0ffa
--- /dev/null
+++ b/am/src/mycpu/timer.c
@@ -0,0 +1,17 @@
+#include <am.h>
+
+void __am_timer_init() {
+}
+
+void __am_timer_uptime(AM_TIMER_UPTIME_T *uptime) {
+  uptime->us = 0;
+}
+
+void __am_timer_rtc(AM_TIMER_RTC_T *rtc) {
+  rtc->second = 0;
+  rtc->minute = 0;
+  rtc->hour   = 0;
+  rtc->day    = 0;
+  rtc->month  = 0;
+  rtc->year   = 1900;
+}
diff --git a/am/src/mycpu/trap.S b/am/src/mycpu/trap.S
new file mode 100644
index 0000000..bc64c53
--- /dev/null
+++ b/am/src/mycpu/trap.S
@@ -0,0 +1,51 @@
+
+#define concat_temp(x, y) x ## y
+#define concat(x, y) concat_temp(x, y)
+#define MAP(c, f) c(f)
+
+#define REGS(f) \
+      f( 1)       f( 3) f( 4) f( 5) f( 6) f( 7) f( 8) f( 9) \
+f(10) f(11) f(12) f(13) f(14) f(15) f(16) f(17) f(18) f(19) \
+f(20) f(21) f(22) f(23) f(24) f(25) f(26) f(27) f(28) f(29) \
+f(30) f(31)
+
+#define PUSH(n) sd concat(x, n), (n * 8)(sp);
+#define POP(n)  ld concat(x, n), (n * 8)(sp);
+
+#define CONTEXT_SIZE ((32 + 3) * 8)
+#define OFFSET_SP     ( 2 * 8)
+#define OFFSET_CAUSE  (32 * 8)
+#define OFFSET_STATUS (33 * 8)
+#define OFFSET_EPC    (34 * 8)
+
+.globl __am_asm_trap
+__am_asm_trap:
+  addi sp, sp, -CONTEXT_SIZE
+
+  MAP(REGS, PUSH)
+
+  mv t0, sp
+  addi t0, t0, CONTEXT_SIZE
+  sd t0, OFFSET_SP(sp)
+
+  csrr t0, mcause
+  csrr t1, mstatus
+  csrr t2, mepc
+
+  sd t0, OFFSET_CAUSE(sp)
+  sd t1, OFFSET_STATUS(sp)
+  sd t2, OFFSET_EPC(sp)
+
+  mv a0, sp
+  jal __am_irq_handle
+
+  ld t1, OFFSET_STATUS(sp)
+  ld t2, OFFSET_EPC(sp)
+  csrw mstatus, t1
+  csrw mepc, t2
+
+  MAP(REGS, POP)
+
+  addi sp, sp, CONTEXT_SIZE
+
+  mret
diff --git a/am/src/mycpu/trm.c b/am/src/mycpu/trm.c
new file mode 100644
index 0000000..0efe6e7
--- /dev/null
+++ b/am/src/mycpu/trm.c
@@ -0,0 +1,27 @@
+#include <am.h>
+#include <klib-macros.h>
+
+extern char _heap_start;
+int main(const char *args);
+
+extern char _pmem_start;
+#define PMEM_SIZE (128 * 1024 * 1024)
+#define PMEM_END  ((uintptr_t)&_pmem_start + PMEM_SIZE)
+
+Area heap = RANGE(&_heap_start, PMEM_END);
+#ifndef MAINARGS
+#define MAINARGS ""
+#endif
+static const char mainargs[] = MAINARGS;
+
+void putch(char ch) {
+}
+
+void halt(int code) {
+  while (1);
+}
+
+void _trm_init() {
+  int ret = main(mainargs);
+  halt(ret);
+}
diff --git a/am/src/mycpu/vme.c b/am/src/mycpu/vme.c
new file mode 100644
index 0000000..5134154
--- /dev/null
+++ b/am/src/mycpu/vme.c
@@ -0,0 +1,18 @@
+#include <am.h>
+
+bool vme_init(void* (*pgalloc_f)(int), void (*pgfree_f)(void*)) {
+  return false;
+}
+
+void protect(AddrSpace *as) {
+}
+
+void unprotect(AddrSpace *as) {
+}
+
+void map(AddrSpace *as, void *va, void *pa, int prot) {
+}
+
+Context *ucontext(AddrSpace *as, Area kstack, void *entry) {
+  return NULL;
+}
diff --git a/klib/src/int64.c b/klib/src/int64.c
index b3b2876..51401f8 100644
--- a/klib/src/int64.c
+++ b/klib/src/int64.c
@@ -705,3 +705,25 @@ COMPILER_RT_ABI si_int __ctzsi2(si_int a) {
   //     }
   return r + ((2 - (x >> 1)) & -((x & 1) == 0));
 }
+
+typedef int si_int;
+typedef long long di_int;
+typedef unsigned su_int;
+#define CHAR_BIT __CHAR_BIT__
+
+
+si_int __ctzdi2(di_int a) {
+  dwords x;
+  x.all = a;
+  const si_int f = -(x.s.low == 0);
+  return __ctzsi2((x.s.high & f) | (x.s.low & ~f)) +
+         (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
+}
+
+si_int __clzdi2(di_int a) {
+  dwords x;
+  x.all = a;
+  const si_int f = -(x.s.high == 0);
+  return __clzsi2((x.s.high & ~f) | (x.s.low & f)) +
+         (f & ((si_int)(sizeof(si_int) * CHAR_BIT)));
+}
diff --git a/scripts/riscv64-mycpu.mk b/scripts/riscv64-mycpu.mk
new file mode 100644
index 0000000..92a553f
--- /dev/null
+++ b/scripts/riscv64-mycpu.mk
@@ -0,0 +1,28 @@
+CROSS_COMPILE := riscv64-linux-gnu-
+COMMON_FLAGS  := -fno-pic -march=rv64ifd -mcmodel=medany
+CFLAGS        += $(COMMON_FLAGS) -static
+ASFLAGS       += $(COMMON_FLAGS) -O0
+LDFLAGS       += -melf64lriscv
+
+AM_SRCS := mycpu/start.S \
+           mycpu/trm.c \
+           mycpu/libgcc/muldi3.S \
+           mycpu/libgcc/div.S \
+           mycpu/ioe.c \
+           mycpu/timer.c \
+           mycpu/input.c \
+           mycpu/cte.c \
+           mycpu/trap.S \
+           mycpu/vme.c \
+           mycpu/mpe.c
+
+CFLAGS    += -fdata-sections -ffunction-sections
+LDFLAGS   += -T $(AM_HOME)/scripts/platform/nemu.ld --defsym=_pmem_start=0x80000000 --defsym=_entry_offset=0x0
+LDFLAGS   += --gc-sections -e _start
+CFLAGS += -DMAINARGS=\"$(mainargs)\"
+.PHONY: $(AM_HOME)/am/src/mycpu/trm.c
+
+image: $(IMAGE).elf
+	@$(OBJDUMP) -d $(IMAGE).elf > $(IMAGE).txt
+	@echo + OBJCOPY "->" $(IMAGE_REL).bin
+	@$(OBJCOPY) -S --set-section-flags .bss=alloc,contents -O binary $(IMAGE).elf $(IMAGE).bin