diff options
| -rw-r--r-- | assembler/assemble.s | 116 | ||||
| -rw-r--r-- | assembler/get_char.s | 21 | ||||
| -rw-r--r-- | assembler/notes | 35 | ||||
| -rw-r--r-- | assembler/string.s | 16 |
4 files changed, 127 insertions, 61 deletions
diff --git a/assembler/assemble.s b/assembler/assemble.s index 96940ea..bf31edf 100644 --- a/assembler/assemble.s +++ b/assembler/assemble.s @@ -1,77 +1,71 @@ -1yyyxxxx Imm yyy = shift amount xxxx = bit-width -00000001 Brackets -0011yyyy Reg yyyy = shift amount -0100yyyy Reg - -MOVS 0x 00 00 88 38 -ADDS 0x 00 00 88 38 -SUBS 0x 00 00 88 38 -CMP 0x 00 00 33 30 -ANDS 0x 00 00 33 30 -ORRS 0x 00 00 33 30 -TST 0x 00 00 33 30 -LSLS 0x 00 E5 33 30 -LSRS 0x 00 E5 33 30 -RORS 0x 00 00 33 30 -LDR 0x E5 33 01 30 -LDRB 0x 36 33 01 30 -STR 0x E5 33 01 30 -STRB 0x 36 33 01 30 -B<c> 0x 00 00 00 88 -B 0x 00 00 00 8B -BX 0x 00 00 00 43 - -// R2 holds the whole word -// R0 holds just the byte -// R1 holds either 3 or 4 -more: - MOVS R0, 0xFF - ANDS R0, R2 - MOVS R1, 0x80 - TST R0, R1 - BNE handle_imm // if IMM - MOVS R1, 0xF0 - ANDS R1, R0 - BEQ handle_brackets // if BRACKETS +assemble: + BL receive_op + LDR R5, =0x20002000 // opcode table + LDR R1, =0x20001000 // opcode buffer base addr +loop: + LDR R0, [R5, 0] // load the string addr + BL string_compare + BEQ match + ADDS R5, 8 // next row of table + LDR R0, =0x20002080 // opcode table end + CMP R5, R0 + BLO loop // Keep going if lower than end + B redo_line // redo line if opcode was not found +match: + LDR R6, [R5, 4] // load the parse instructions +main_loop: + MOVS R0, 0xFF // lsb mask + ANDS R0, R6 // store in R0 + MOVS R1, 0x80 // bit 7 mask + TST R0, R1 // compare (AND) to R0 byte + BNE handle_imm // if IMM (== 1) + LSRS R0, 4 // R0 hold 3 or 4 (or 0) + BEQ handle_brackets // if BRACKETS (== 0) handle_reg: - LSRS R1, 4 - MOVS R3, 0x0F - ANDS R0, R3 - // R1 = 3 or 4 - // R0 = shift amount - BL register + BL register // result is put in R4 + MOVS R0, 0x0F // lower nibble mask + ANDS R0, R6 // store shift amount in R0 + LSLS R4, R0 // shift the result by the shift amount + ORRS R5, R4 // OR the register code into the word under construction B done_stuff - handle_imm: - BL octal - B done_stuff - -handle_brackets: - // expect bracket - // echo bracket - LSRS R2, 0x8 - BEQ next_instr - Back - ... - + MOVS R1, 0x0F // lower nibble mask + ANDS R0, R1 // store immediate width in R0 + BL octal // result is put in R4 + MOVS R0, 0x7F // least significant 7 bits mask + ANDS R0, R6 // store ls 7 bits in R0 + LSRS R0, 4 // shift right to get shift amount + LSLS R4, R0 // shift the result by the shift amount done_stuff: - LSRS R2, 0x4 - BEQ done - MOVS R0, 0 + LSRS R6, 0x8 // get next parse instruction + BEQ done // if it's zero there are no more things to parse + MOVS R0, 0 // copy the end_char into R0 ORRS R0, R9 BL uart_send // echo the comma (or bracket) -expect: +10: BL get_char MOVS R1, ' // space char CMP R0, R1 - BNE expect // keep trying if not space + BNE 10b // keep trying if not space BL uart_send // echo the space - B more + B main_loop +handle_brackets: + BL get_char // char in R0 + MOVS R1, '[ // open bracket + CMP R0, R1 + BNE handle_brackets // keep trying if not bracket + BL uart_send // echo bracket + MOVS R8, 1 // 1 means we are now in brackets + LSRS R6, 0x8 // get next parse instruction + BNE main_loop done: TST R8, R8 // R8 == whether we are in bracket or not BEQ no_brackets - MOVS R0, '] + MOVS R0, '] // echo bracket BL uart_send no_bracket: - // echo carriage return + newline + MOVS R0, '\r // send carriage return + BL uart_send + MOVS R0, '\n // send newline + BL uart_send B next_instr diff --git a/assembler/get_char.s b/assembler/get_char.s new file mode 100644 index 0000000..f1f43e7 --- /dev/null +++ b/assembler/get_char.s @@ -0,0 +1,21 @@ +// R9: end_char +get_char: + PUSH {LR} + BL uart_recv + MOVS R1, 025 // ^U (NAK) + CMP R0, R1 + BEQ redo_line + MOVS R1, 004 // ^D (EOT) + CMP R0, R1 + BEQ done_for_real + CMP R0, R9 + POP {PC} + +get_line: + BL get_char + ... + B get_line + +redo_line: + ... + B get_line diff --git a/assembler/notes b/assembler/notes new file mode 100644 index 0000000..6206eff --- /dev/null +++ b/assembler/notes @@ -0,0 +1,35 @@ +Clobber +R0: arg1, uart result +R1: arg2 +R2: +R3: shift_amount +------------- +Save +R4: octal result, register result +R5: word under construction +R6: parse instructions +R8: +R9: end_char + +1yyyxxxx Imm yyy = shift amount xxxx = bit-width +00000001 Brackets +0011yyyy Reg yyyy = shift amount +0100yyyy Reg + +MOVS 0x 00 00 88 38 +ADDS 0x 00 00 88 38 +SUBS 0x 00 00 88 38 +CMP 0x 00 00 33 30 +ANDS 0x 00 00 33 30 +ORRS 0x 00 00 33 30 +TST 0x 00 00 33 30 +LSLS 0x 00 E5 33 30 +LSRS 0x 00 E5 33 30 +RORS 0x 00 00 33 30 +LDR 0x E5 33 01 30 +LDRB 0x 36 33 01 30 +STR 0x E5 33 01 30 +STRB 0x 36 33 01 30 +B<c> 0x 00 00 00 88 +B 0x 00 00 00 8B +BX 0x 00 00 00 43 diff --git a/assembler/string.s b/assembler/string.s new file mode 100644 index 0000000..0ed7ca3 --- /dev/null +++ b/assembler/string.s @@ -0,0 +1,16 @@ +// R0 : string1 address +// R1 : string2 address +// Result in R0 +string_compare: + MOVS R4, 0 +loop: + LDRB R2, [R0, R4] + LDRB R3, [R1, R4] + CMP R2, R3 + BNE done + CMP R2, 0 + BEQ done + ADDS R4, 1 + B loop +done: + BX LR |