diff options
| -rw-r--r-- | README.md | 3 | ||||
| -rw-r--r-- | date.s | 36 | ||||
| -rw-r--r-- | instructions/LSR.ts | 1 | ||||
| -rw-r--r-- | runtime.ts | 8 |
4 files changed, 43 insertions, 5 deletions
diff --git a/README.md b/README.md index 5a6ff4c..37c870a 100644 --- a/README.md +++ b/README.md @@ -28,4 +28,5 @@ commands: - `k[NUM]` - skip - `r[ADR]` - breakpoint - `g[ADR]` - goto, change PC - - `I[INS]` - breakpoint instruction \ No newline at end of file + - `I[INS]` - breakpoint instruction + \ No newline at end of file diff --git a/date.s b/date.s new file mode 100644 index 0000000..afd6717 --- /dev/null +++ b/date.s @@ -0,0 +1,36 @@ +;* This routine works for any date from 1900-03-01 to 2155-12-31. +;* No range checking is done, so validate input before calling. +;* +;* I use the formula +;* Weekday = (day + offset[month] + year + year/4 + fudge) mod 7 +;* where the value of fudge depends on the century. +;* +;* Input: Y = year (0=1900, 1=1901, ..., 255=2155) +;* X = month (1=Jan, 2=Feb, ..., 12=Dec) +;* A = day (1 to 31) +;* +;* Output: Weekday in A (0=Sunday, 1=Monday, ..., 6=Saturday) + +TMP EQU $6 ; Temporary storage + +WEEKDAY: + CPX #3 ; Year starts in March to bypass + BCS MARCH ; leap year problem + DEY ; If Jan or Feb, decrement year +MARCH EOR #$7F ; Invert A so carry works right + CPY #200 ; Carry will be 1 if 22nd century + ADC MTAB-1,X ; A is now day+month offset + STA TMP + TYA ; Get the year + JSR MOD7 ; Do a modulo to prevent overflow + SBC TMP ; Combine with day+month + STA TMP + TYA ; Get the year again + LSR ; Divide it by 4 + LSR + CLC ; Add it to y+m+d and fall through + ADC TMP +MOD7 ADC #7 ; Returns (A+3) modulo 7 + BCC MOD7 ; for A in 0..255 + RTS +MTAB DB 1,5,6,3,1,5,3,0,4,2,6,4 ; Month offsets diff --git a/instructions/LSR.ts b/instructions/LSR.ts index 61adadb..b907e47 100644 --- a/instructions/LSR.ts +++ b/instructions/LSR.ts @@ -8,6 +8,7 @@ export default function (this: The65c02, mode: string) { this.zero = result == 0 this.carry = (mem & 1) != 0 this.regA.set(result & 0xFF); + this.programCounter.increment() } else { const addr = this.getAddr(mode) this.io.address.set(addr); diff --git a/runtime.ts b/runtime.ts index 2e6723f..ccb9dae 100644 --- a/runtime.ts +++ b/runtime.ts @@ -24,13 +24,13 @@ const binStart = parseInt(args.b ?? args.binStart ?? '8000', 16) if (Number.isNaN(binStart)) throw 'binStart is NaN!' -// mem address $0000 -ram[0xFFFC] = binStart & 0x00FF -ram[0xFFFD] = binStart & 0xFF00 - // read code from file const code = Deno.readFileSync(args._.toString() || 'msbasic/tmp/eater.bin') +// mem address $0000 +ram[0xFFFC] = binStart & 0x00FF +ram[0xFFFD] = (binStart & 0xFF00) >> 8 + // write code to ram before execution for (let offset = 0; offset < code.length; offset++) { const byte = code[offset]; |