Created
September 3, 2018 03:49
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Generate random, yet compressible data.
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| static void gen_pre_buf(uint8_t * pre_buf, uint8_t (*get_byte)(void *), void * opaque) { | |
| int i; | |
| memset(pre_buf, 0, 1024); | |
| for (i = 0; i < 256; i++) { | |
| pre_buf[i + 256] = i; | |
| pre_buf[i * 2 + 512] = i; | |
| } | |
| for (i = 0; i < 384; i++) { | |
| uint8_t l = get_byte(opaque); | |
| uint8_t b = get_byte(opaque); | |
| pre_buf[l * 4 + (i & 3)] = b; | |
| } | |
| } | |
| void gen_data(uint8_t * out, size_t out_size, uint8_t (*get_byte)(void *), void * opaque) { | |
| gen_pre_buf(out, get_byte, opaque); | |
| out += 1024; | |
| while (1) { | |
| uint8_t mask; | |
| int i; | |
| mask = get_byte(opaque); | |
| for (i = 0; i < 8; i++) { | |
| if (mask & 1) { | |
| uint8_t b1, b2; | |
| uint16_t n; | |
| uint16_t offset; | |
| uint8_t * ptr; | |
| b1 = get_byte(opaque); | |
| b2 = get_byte(opaque); | |
| n = (b1 << 8) | b2; | |
| offset = (n >> 6) + 1; | |
| n &= 0x3f; | |
| n += 3; | |
| ptr = out - offset; | |
| if (n > out_size) | |
| n = out_size; | |
| out_size -= n; | |
| while (n--) { | |
| *out++ = *ptr++; | |
| } | |
| } else { | |
| *out++ = get_byte(opaque); | |
| out_size--; | |
| } | |
| if (out_size == 0) | |
| return; | |
| mask >>= 1; | |
| } | |
| } | |
| } |
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