63 lines
2.2 KiB
C
63 lines
2.2 KiB
C
#pragma once
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#define V90_SAMPLE_RATE 8000
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#define TREILLIS_MAX_DEPTH 4
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/* ring buffer size of the previous ucodes : must be a power of two */
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#define UCODE_BUF_SIZE (TREILLIS_MAX_DEPTH * 8)
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/* state of the signal processing part of the V90 modem */
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typedef struct V90EncodeState {
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struct sm_state *sm;
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int alaw; /* true=alaw, false=ulaw */
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/* frame parameters (a frame = 6 PAM values) */
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int S; /* sign bits (3 <= S <= 6) */
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int K; /* number of bits for the ring coder */
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int a1, a2, b1, b2; /* spectral conformer parameters */
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int M[6]; /* ring size */
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u8 m_to_ucode[6][128]; /* encoding table */
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int ld; /* depth for spectral shaping (0 <= ld <= 3) */
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/* sign mapper */
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int ucode_ptr; /* index of the first pam value of the
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current mapping frame */
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u8 ucode[UCODE_BUF_SIZE]; /* current output of the modulator */
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u8 pp[UCODE_BUF_SIZE]; /* corresponding signs (grouped by frame) */
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int last_sign; /* sign of the last computed frame */
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/* spectral shaping treillis */
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u8 t; /* signs of the frame */
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s16 x; /* last x value: not stricly needed, but simply the treillis computation */
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s16 y; /* memory for spectral shaping filter */
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s16 v; /* idem */
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s16 w; /* idem */
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int Q; /* current shaping treillis state
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(with a delay of ld) */
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const s16 *ucode_to_linear; /* table to retrieve the linear values from ucodes */
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} V90EncodeState;
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extern const s16 v90_ulaw_ucode_to_linear[128];
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extern const s16 v90_alaw_ucode_to_linear[128];
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typedef struct V90DecodeState {
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struct sm_state *sm;
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int alaw; /* true=alaw, false=ulaw */
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/* frame parameters (a frame = 6 PAM values) */
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int S; /* sign bits (3 <= S <= 6) */
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int K; /* number of bits for the ring coder */
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int M[6]; /* ring size */
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u8 ucode_used[6][128];
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s16 m_to_linear[6][128]; /* give the estimated linear value of each received modulo */
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int ld;
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s8 a1, a2, b1, b2;
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int last_sign;
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int t;
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int Q;
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const s16 *ucode_to_linear; /* table to retrieve the linear values from ucodes */
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} V90DecodeState;
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