projects / vvhitespace / blame
| Commit | Line | Data |
|---|---|---|
| b6bea2cf AT |
1 | #ifndef VVS_STDLIB_CONVERT |
| 2 | #define VVS_STDLIB_CONVERT | |
| 3 | ||
| 4 | @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ | |
| 5 | @ Name: | |
| 6 | @ atoi (110000) | |
| 7 | @ Description: | |
| 8 | @ Convert null-terminated ASCII string to integer. | |
| 9 | @ Result is negative if leading character is a hyphen ('-'). | |
| 10 | @ Result is positive if leading character is a plus sign ('+') or number. | |
| 11 | @ Excluding the sign, parsing halts on the first non-numeric ASCII character. | |
| 12 | @ Since all possible return values are valid, this subroutine simply returns | |
| 13 | @ zero if no parseable number was found. Any stronger validity checks are the | |
| 14 | @ responsibility of the caller. Similarly, no overflow checks are performed. | |
| 15 | @ In addition to returning the parsed integer, also returns a pointer to the | |
| 16 | @ first character after the parsed integer. | |
| 17 | @ Call Stack: | |
| 18 | @ pointer to first character <-- TOS | |
| 19 | @ Return Stack: | |
| 20 | @ integer | |
| 21 | @ pointer to last parsed character <-- TOS | |
| 22 | @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ | |
| 23 | #include <stack.pvvs> | |
| 24 | #include <string.pvvs> | |
| 25 | NSSVTTSSSSN | Mark: 110000 (atoi) | |
| 26 | ||
| 27 | @ Check the first character and create a 'sign' flag on the stack. | |
| 28 | @ Update the pointer to point to the first numeric character. | |
| 29 | SNS | DUP | |
| 30 | TTT | LOAD | |
| 31 | SSSSSTSTTSTN | PUSH 45 (ASCII '-') | |
| 32 | TSST | SUBTRACT | |
| 33 | NTSSSTTSSSSSSSSSSSSN | BRZ > 00110000 00000000 (found_minus_sign) | |
| 34 | SNS | DUP | |
| 35 | TTT | LOAD | |
| 36 | SSSSSTSTSTTN | PUSH 43 (ASCII '+') | |
| 37 | TSST | SUBTRACT | |
| 38 | NTSSSTTSSSSSSSSSSSTN | BRZ > 00110000 00000001 (found_plus_sign) | |
| 39 | NSNSSTTSSSSSSSSSSTSN | JMP > 00110000 00000010 (found_digit) | |
| 40 | NSSVSSTTSSSSSSSSSSSTN | Mark: 00110000 00000001 (found_plus_sign) | |
| 41 | SSSTN | PUSH +1 | |
| 42 | TSSS | ADD | |
| 43 | NSSVSSTTSSSSSSSSSSTSN | Mark: 00110000 00000010 (found_digit) | |
| 44 | SSSTN | PUSH +1 (sign_flag) | |
| 45 | SNT | SWAP | |
| 46 | NSNSSTTSSSSSSSSSSTTN | JMP > 00110000 00000011 (done_with_sign_flag) | |
| 47 | NSSVSSTTSSSSSSSSSSSSN | Mark: 00110000 00000000 (found_minus_sign) | |
| 48 | SSSTN | PUSH +1 | |
| 49 | TSSS | ADD | |
| 50 | SSTTN | PUSH -1 (sign_flag) | |
| 51 | SNT | SWAP | |
| 52 | NSSVSSTTSSSSSSSSSSTTN | Mark: 00110000 00000011 (done_with_sign_flag) | |
| 53 | ||
| 54 | @ Create an accumulator on the TOS. | |
| 55 | SSSSN | PUSH 0 (accumulator) | |
| 56 | ||
| 57 | @ Main loop examines string one character at a time, building result in accumulator. | |
| 58 | @ TOS> accumulator, string_ptr, sign_flag | |
| 59 | NSSVSSTTSSSSSSSSSTSSN | Mark: 00110000 00000100 (atoi:main_loop) | |
| 60 | SSSTSN | PUSH +2 | |
| 61 | NSTTTSSN | JSR > 1100 (deepdup) | |
| 62 | TTT | LOAD | |
| 63 | SNS | DUP | |
| 64 | NSTTSSSSTN | JSR > 100001 (isdigit) | |
| 65 | NTSSSTTSSSSSSSSSTSTN | BRZ > 00110000 00000101 (found_end_of_number) | |
| 66 | SSSSSTTSSSSN | PUSH 48 (ASCII '0') | |
| 67 | TSST | SUBTRACT | |
| 68 | SNT | SWAP | |
| 69 | SSSTSTSN | PUSH 10 | |
| 70 | TSSN | MULTIPLY | |
| 71 | TSSS | ADD | |
| 72 | SNT | SWAP | |
| 73 | SSSTN | PUSH 1 | |
| 74 | TSSS | ADD | |
| 75 | SNT | SWAP | |
| 76 | NSNSSTTSSSSSSSSSTSSN | JMP > 00110000 00000100 (atoi:main_loop) | |
| 77 | ||
| 78 | @ Clean up and return | |
| 79 | @ TOS> character, accumulator, string_ptr, sign_flag | |
| 80 | NSSVSSTTSSSSSSSSSTSTN | Mark: 00110000 00000101 (found_end_of_number) | |
| 81 | SNN | DROP | |
| 82 | SSSTTN | PUSH 3 | |
| 83 | NSTTSTTN | JSR > 1011 (stackrotatereverse) | |
| 84 | TSSN | MULTIPLY | |
| 85 | SNT | SWAP | |
| 86 | NTN | RTS | |
| 87 | ||
| 88 | #endif |