Created
March 24, 2021 18:01
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Sector prober
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| #include <stdint.h> | |
| #include <stdio.h> | |
| static inline uint8_t from_BCD(uint8_t x) { return ((x & 0x0f) + ((x & 0xf0) >> 4) * 10); } | |
| static inline uint32_t from_MSF(uint8_t m, uint8_t s, uint8_t f) { | |
| return (from_BCD(m) * 60 + from_BCD(s)) * 75 + from_BCD(f); | |
| } | |
| static void probe_sector(const uint8_t* sector, unsigned expected_lba) { | |
| // do we have a sync pattern? | |
| if (*sector++ != 0x00) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0xff) return; | |
| if (*sector++ != 0x00) return; | |
| // next up: reading the MSF and mode | |
| uint8_t m = *sector++; | |
| uint8_t s = *sector++; | |
| uint8_t f = *sector++; | |
| uint8_t mode = *sector++; | |
| // if sector isn't a mode2 sector, go away | |
| if (mode != 2) return; | |
| // if the MSF isn't what we expect, go away | |
| if (from_MSF(m, s, f) != expected_lba) return; | |
| // if the subheader isn't properly duplicated, go away | |
| const uint8_t* subheader = sector; | |
| if (subheader[0] != subheader[4]) return; | |
| if (subheader[1] != subheader[5]) return; | |
| if (subheader[2] != subheader[6]) return; | |
| if (subheader[3] != subheader[7]) return; | |
| // now decoding sector information | |
| uint8_t FN = subheader[0]; | |
| uint8_t CN = subheader[1]; | |
| uint8_t SM = subheader[2]; | |
| uint8_t CI = subheader[3]; | |
| unsigned fEOR = (SM >> 0) & 1; | |
| unsigned fV = (SM >> 1) & 1; | |
| unsigned fA = (SM >> 2) & 1; | |
| unsigned fD = (SM >> 3) & 1; | |
| unsigned fT = (SM >> 4) & 1; | |
| unsigned fF = (SM >> 5) & 1; | |
| unsigned fRT = (SM >> 6) & 1; | |
| unsigned fEOF = (SM >> 7) & 1; | |
| printf("Sector %02x:%02x:%02x: FN: %i, CN: %i, SM: <EOR:%i,V:%i,A:%i,D:%i,T:%i,F:%i,RT:%i,EOF:%i>, CI: %02x\n", m, s, f, FN, CN, fEOR, fV, fA, fD, fT, fF, fRT, fEOF, CI); | |
| if (fA) { | |
| unsigned S = (CI >> 0) & 3; | |
| unsigned FS = (CI >> 2) & 3; | |
| unsigned BL = (CI >> 4) & 3; | |
| unsigned E = (CI >> 6) & 1; | |
| const char * sS; | |
| const char * sFS; | |
| const char * sBL; | |
| const char * sE; | |
| switch (S) { | |
| case 0: | |
| sS = "Mono"; | |
| break; | |
| case 1: | |
| sS = "Stereo"; | |
| break; | |
| case 2: | |
| sS = "Unknown Stereo Setting 2"; | |
| break; | |
| case 3: | |
| sS = "Unknown Stereo Setting 3"; | |
| break; | |
| } | |
| switch (FS) { | |
| case 0: | |
| sFS = "37.8kHz"; | |
| break; | |
| case 1: | |
| sFS = "18.9kHz"; | |
| break; | |
| case 2: | |
| sFS = "Unknown sampling frequency 2"; | |
| break; | |
| case 3: | |
| sFS = "Unknown sampling frequency 3"; | |
| break; | |
| } | |
| switch (BL) { | |
| case 0: | |
| sBL = "4 bits"; | |
| break; | |
| case 1: | |
| sBL = "8 bits"; | |
| break; | |
| case 2: | |
| sBL = "Unknown bit length 2"; | |
| break; | |
| case 3: | |
| sBL = "Unknown bit length 3"; | |
| break; | |
| } | |
| switch (E) { | |
| case 0: | |
| sE = "Emphasis disabled"; | |
| break; | |
| case 1: | |
| sE = "Emphasis enabled"; | |
| break; | |
| } | |
| printf(" --> XA: %s; %s; %s; %s\n", sS, sFS, sBL, sE); | |
| } | |
| } | |
| int main(int argc, char** argv) { | |
| if (argc != 2) { | |
| fprintf(stderr, "Need one argument with the iso filename.\n"); | |
| return 1; | |
| } | |
| FILE* in = fopen(argv[1], "rb"); | |
| if (!in) { | |
| fprintf(stderr, "Failed to open input file %s\n", argv[1]); | |
| return 1; | |
| } | |
| uint8_t buffer[2352]; | |
| unsigned lba = 150; | |
| while (!feof(in)) { | |
| int r = fread(buffer, 2352, 1, in); | |
| if (!r) return 1; | |
| probe_sector(buffer, lba++); | |
| } | |
| return 0; | |
| } |
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Glossary:
FN = File Number
CN = Channel Number
SM = Sub Mode
CI = Channel Information
EOR = End of Record
V = Video
A = Audio
D = Data
T = Trigger
F = Form
RT = Real Time Sector
EOF = End Of File