f6612fb33b
A lot of clean ups from waltje; Start of a directory structure for the code, thanks to waltje.
64 lines
2.3 KiB
C
64 lines
2.3 KiB
C
/* Copyright holders: Sarah Walker
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see COPYING for more details
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*/
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/*PCem v8.1 by Tom Walker
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ICD2061 clock generator emulation
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Used by ET4000w32/p (Diamond Stealth 32)*/
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#include "../ibm.h"
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#include "vid_icd2061.h"
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void icd2061_write(icd2061_t *icd2061, int val)
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{
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int q, p, m, a;
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if ((val & 1) && !(icd2061->state & 1))
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{
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if (!icd2061->status)
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{
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if (val & 2)
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icd2061->unlock++;
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else
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{
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if (icd2061->unlock >= 5)
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{
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icd2061->status = 1;
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icd2061->pos = 0;
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}
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else
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icd2061->unlock = 0;
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}
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}
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else if (val & 1)
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{
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icd2061->data = (icd2061->data >> 1) | (((val & 2) ? 1 : 0) << 24);
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icd2061->pos++;
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if (icd2061->pos == 26)
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{
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a = (icd2061->data >> 21) & 0x7;
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if (!(a & 4))
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{
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q = (icd2061->data & 0x7f) - 2;
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m = 1 << ((icd2061->data >> 7) & 0x7);
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p = ((icd2061->data >> 10) & 0x7f) - 3;
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if (icd2061->ctrl & (1 << a))
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p <<= 1;
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icd2061->freq[a] = ((double)p / (double)q) * 2.0 * 14318184.0 / (double)m;
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}
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else if (a == 6)
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{
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icd2061->ctrl = val;
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}
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icd2061->unlock = icd2061->data = 0;
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icd2061->status = 0;
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}
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}
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}
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icd2061->state = val;
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}
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double icd2061_getfreq(icd2061_t *icd2061, int i)
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{
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return icd2061->freq[i];
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}
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