ISO/IEC 10918-1 : 1993(E)
D.2.5
Probability estimation in the decoder
The procedures defined for obtaining a new LPS probability estimate in the encoder are also used in the decoder.
D.2.6
Renormalization in the decoder
The Renorm_d procedure for the decoder renormalization is shown in Figure D.19. CT is a counter which keeps track of
the number of compressed bits in the C-low section of the C-register. When CT is zero, a new byte is inserted into C-low
by the procedure Byte_in and CT is reset to 8.
Both the probability interval register A and the code register C are shifted, one bit at a time, until A is no longer less than
X'8000'.
TISO1190-93/d057
Renorm_d
Yes
No
Byte_in
CT = 8
Done
Yes
No
A = SLL A 1
C = SLL C 1
CT = CT ­ 1
CT = 0
?
A < X'8000'
?
Figure D.19 ­ Decoder renormalization procedure
Figure D.19 [D57], = 16.5 cm = 645.%
CCITT Rec. T.81 (1992 E)
73
 [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] [54] [55] [56] [57] [58] [59] [60] [61] [62] [63] [64] [65] [66] [67] [68] [69] [70] [71] [72] [73] [74] [75] [76] [77] [78] [79] [80] [81] [82] [83] [84] [85] [86] [87] [88] [89] [90] [91] [92] [93] [94] [95] [96] [97] [98] [99] [100] [101] [102] [103] [104] [105] [106] [107] [108] [109] [110] [111] [112] [113] [114] [115] [116] [117] [118] [119] [120] [121] [122] [123] [124] [125] [126] [127] [128] [129] [130] [131] [132] [133] [134] [135] [136] [137] [138] [139] [140] [141] [142] [143] [144] [145] [146] [147] [148] [149] [150] [151] [152] [153] [154] [155] [156] [157] [158] [159] [160] [161] [162] [163] [164] [165] [166] [167] [168] [169] [170] [171] [172] [173] [174] [175] [176] [177] [178] [179] [180] [181] [182] [183] [184] [185] [186]