hence/examples/forth.asm

@ hence core lib
core:
  core_mem:
    .define CORE_MEM_PRG, (0 * 1024)
    .define CORE_MEM_ST, (32 * 1024)
    .define CORE_MEM_MEM, (40 * 1024)
    .define CORE_MEM_OUT, (56 * 1024)
    .define CORE_MEM_CHR, (56 * 1024 + 1)
    .define CORE_MEM_KEY, (56 * 1024 + 2)

  core_reg:
    .define CORE_REG_PC, 0x0
    .define CORE_REG_OPC, 0x1
    .define CORE_REG_ARG, 0x2
    .define CORE_REG_S, 0x3
    .define CORE_REG_SP, 0x4
    .define CORE_REG_A, 0x5
    .define CORE_REG_B, 0x6
    .define CORE_REG_C, 0x7
    .define CORE_REG_D, 0x8

  core_alu:
    .define CORE_ALU_NOT, 0x00
    .define CORE_ALU_AND, 0x01
    .define CORE_ALU_OR, 0x02
    .define CORE_ALU_XOR, 0x03
    .define CORE_ALU_LSH, 0x04
    .define CORE_ALU_RSH, 0x05
    .define CORE_ALU_ADD, 0x06
    .define CORE_ALU_SUB, 0x07
    .define CORE_ALU_MUL, 0x08
    .define CORE_ALU_DIV, 0x09
    .define CORE_ALU_CMP, 0x0a
    .define CORE_ALU_EQ, 0x0b
    .define CORE_ALU_LT, 0x0c
    .define CORE_ALU_GT, 0x0d
    .define CORE_ALU_LEQ, 0x0e
    .define CORE_ALU_GEQ, 0x0f
    .define CORE_ALU_BOL, 0x10
    .define CORE_ALU_INV, 0x11
    .define CORE_ALU_RND, 0x12

@ hence standard lib
STD:
  .define STD_U8_MAX, 0xff
  .define STD_U16_MAX, 0xffff

  .macro std_stop
    ts 0xffff
    tlr CORE_REG_PC
  .macroend

forth:
  .define FORTH_MEM_INPUT_SIZE, 16
  .define FORTH_MEM_INPUT_DYN_SIZE, CORE_MEM_MEM
  .define FORTH_MEM_INPUT_START, (FORTH_MEM_INPUT_DYN_SIZE + 1)
  .define FORTH_MEM_INPUT_END, (FORTH_MEM_INPUT_START + FORTH_MEM_INPUT_SIZE)

.define jump_main, (CORE_MEM_ST - 3 - 1)

ts jump_main
tlr CORE_REG_PC

end_input:
  dbg

main:
  @ loop body
  loop:
    @ read key from stdin
    ts CORE_MEM_KEY
    get

    @ check if key is newline (0x0a)
    tlr CORE_REG_D @ store in register D because register A is used later on
    tlr CORE_REG_A @ store in register A as input for ALU
    ts "\n" @ store newline in TMP
    tlr CORE_REG_B @ store newline in register B as input for ALU
    ts CORE_ALU_EQ @ ALU equal operation
    alu @ run ALU

    @ go back to loop start if pressed key is newline
    tlr CORE_REG_A @ store result of ALU operation in TMP
    @ ts loop @ load memory address of loop start into TMP 
    ts 0
    tls
    ts jump_switch
    tls
    ts end_input
    tlrc CORE_REG_PC @ set register PC to loop start address if result is true
    pop

    tlr CORE_REG_A
    ts 0
    tlrc CORE_REG_C

    @ print out char
    tsr CORE_REG_D @ get char
    tlr CORE_REG_A @ load char into register A
    ts CORE_MEM_CHR @ set TMP to char print memory address
    set @ print char

  @ increment counter by one
  tsr CORE_REG_C
  tlr CORE_REG_A
  ts 1
  tlr CORE_REG_B
  ts CORE_ALU_ADD
  alu
  tlr CORE_REG_C
  tlr CORE_REG_A

  ts FORTH_MEM_INPUT_SIZE
  tlr CORE_REG_B
  ts CORE_ALU_LT
  alu
  tlr CORE_REG_A
  ts loop
  tlrc CORE_REG_PC

  ts "\n"
  tlr CORE_REG_A
  ts CORE_MEM_CHR
  set

  tsr CORE_REG_C
  tls
  dbg
  pop

  ts 0
  tlr CORE_REG_C
  ts loop
  tlr CORE_REG_PC

@ .std_stop

@ set PC to maximum for u16 and therefore stops program execution
ts 0xffff @ load 0xffff into TMP
tlr CORE_REG_PC @ store value of TMP into register PC

jump_switch:
  dbg

.org jump_main
  ts main
  tlr CORE_REG_PC