diff options
| -rw-r--r-- | lpg/libqr/code-create.c | 100 | ||||
| -rw-r--r-- | lpg/libqr/qr/code.h | 8 |
2 files changed, 102 insertions, 6 deletions
diff --git a/lpg/libqr/code-create.c b/lpg/libqr/code-create.c index 5582a30..9ce46f7 100644 --- a/lpg/libqr/code-create.c +++ b/lpg/libqr/code-create.c @@ -19,6 +19,12 @@ static int count_locators(const struct qr_bitmap * bmp); static int calc_bw_balance(const struct qr_bitmap * bmp); static int get_px(const struct qr_bitmap * bmp, int x, int y); static int get_mask(const struct qr_bitmap * bmp, int x, int y); +static int draw_format(struct qr_bitmap * bmp, + struct qr_code * code, + enum qr_ec_level ec, + int mask); +static int calc_format_bits(enum qr_ec_level ec, int mask); +static unsigned long gal_residue(unsigned long a, unsigned long m); /* FIXME: the static functions should be in a better * order, with prototypes. @@ -63,6 +69,7 @@ static void draw_locator(struct qr_bitmap * bmp, int x, int y) } static int draw_functional(struct qr_code * code, + enum qr_ec_level ec, unsigned int mask) { struct qr_bitmap * bmp; @@ -85,8 +92,13 @@ static int draw_functional(struct qr_code * code, } /* XXX: alignment pattern */ - /* XXX: mask, format info */ + /* Format info */ + setpx(bmp, 8, dim - 8); + if (draw_format(bmp, code, ec, mask) != 0) + return -1; + + /* Merge data */ qr_bitmap_merge(bmp, code->modules); qr_bitmap_destroy(code->modules); code->modules = bmp; @@ -261,7 +273,7 @@ struct qr_code * qr_code_create(enum qr_ec_level ec, if (mask < 0) goto fail; - if (draw_functional(code, mask) != 0) + if (draw_functional(code, ec, mask) != 0) goto fail; exit: @@ -466,3 +478,87 @@ static int get_mask(const struct qr_bitmap * bmp, int x, int y) return bmp->mask[off] & bit; } +static int draw_format(struct qr_bitmap * bmp, + struct qr_code * code, + enum qr_ec_level ec, + int mask) +{ + int i; + size_t dim; + long bits; + + dim = bmp->width; + + bits = calc_format_bits(ec, mask); + if (bits < 0) + return -1; + + for (i = 0; i < 8; ++i) { + if (bits & 0x1) { + setpx(bmp, 8, i); + setpx(bmp, dim - 1 - i, 8); + } + bits >>= 1; + } + + for (i = 0; i < 7; ++i) { + if (bits & 0x1) { + setpx(bmp, 8, dim - 7 + i); + setpx(bmp, 6 - i + (i == 0), 8); + } + bits >>= 1; + } + + /* XXX: size info for 7~40 */ + + return 0; +} + +static int calc_format_bits(enum qr_ec_level ec, int mask) +{ + int bits; + + bits = (ec & 0x3) << 3 | (mask & 0x7); + + /* Compute (15, 5) BCH code with + * G(x) = x^10 + x^8 + x^5 + x^4 + x^2 + x + 1 + */ + + bits <<= 15 - 5; + bits |= (unsigned int)gal_residue(bits, 0x537); + + /* XOR mask: 101 0100 0001 0010 */ + bits ^= 0x5412; + + return bits; +} + +/* Calculate the residue of a modulo m */ +static unsigned long gal_residue(unsigned long a, + unsigned long m) +{ + unsigned long o = 1; + int n = 1; + + /* Find one past the highest bit of the modulus */ + while (m & ~(o - 1)) + o <<= 1; + + /* Find the highest n such that O(m * x^n) <= O(a) */ + while (a & ~(o - 1)) { + o <<= 1; + ++n; + } + + /* For each n, try to reduce a by (m * x^n) */ + while (n--) { + o >>= 1; + + /* o is the highest bit of (m * x^n) */ + if (a & o) + a ^= m << n; + } + + return a; +} + diff --git a/lpg/libqr/qr/code.h b/lpg/libqr/qr/code.h index 56a9884..dba0040 100644 --- a/lpg/libqr/qr/code.h +++ b/lpg/libqr/qr/code.h @@ -5,10 +5,10 @@ #include "types.h" enum qr_ec_level { - QR_EC_LEVEL_L, - QR_EC_LEVEL_M, - QR_EC_LEVEL_Q, - QR_EC_LEVEL_H + QR_EC_LEVEL_L = 0x1, + QR_EC_LEVEL_M = 0x0, + QR_EC_LEVEL_Q = 0x3, + QR_EC_LEVEL_H = 0x2 }; struct qr_code * qr_code_create(enum qr_ec_level ec, |