From 6fd10cdacb5cbe47a4fc339c20a733d4a9a384a1 Mon Sep 17 00:00:00 2001
From: Takamichi Horikawa <takamichiho@gmail.com>
Date: Sat, 26 Nov 2016 20:57:57 +0900
Subject: initial

---
 libopna/opnaadpcm.c | 208 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 208 insertions(+)
 create mode 100644 libopna/opnaadpcm.c

(limited to 'libopna/opnaadpcm.c')

diff --git a/libopna/opnaadpcm.c b/libopna/opnaadpcm.c
new file mode 100644
index 0000000..1157b56
--- /dev/null
+++ b/libopna/opnaadpcm.c
@@ -0,0 +1,208 @@
+#include "opnaadpcm.h"
+
+enum {
+  C1_START = 0x80,
+  C1_REC = 0x40,
+  C1_MEMEXT = 0x20,
+  C1_REPEAT = 0x10,
+  C1_RESET = 0x01,
+  C1_MASK = 0xf9,
+};
+
+enum {
+  C2_L = 0x80,
+  C2_R = 0x40,
+  C2_8BIT = 0x02,
+  C2_MASK = 0xcf,
+};
+
+static const uint8_t adpcm_table[8] = {
+  57, 57, 57, 57, 77, 102, 128, 153,
+};
+
+void opna_adpcm_reset(struct opna_adpcm *adpcm) {
+  adpcm->control1 = 0;
+  adpcm->control2 = 0;
+  adpcm->vol = 0;
+  adpcm->delta = 0;
+  adpcm->start = 0;
+  adpcm->end = 0;
+  adpcm->limit = 0;
+  adpcm->ramptr = 0;
+  adpcm->step = 0;
+  adpcm->ram = 0;
+  adpcm->acc = 0;
+  adpcm->prev_acc = 0;
+  adpcm->adpcmd = 127;
+  adpcm->out = 0;
+}
+
+static uint32_t addr_conv(const struct opna_adpcm *adpcm, uint16_t a) {
+  uint32_t a32 = a;
+  return (adpcm->control2 & C2_8BIT) ? (a32<<6) : (a32<<3);
+}
+static uint32_t addr_conv_e(const struct opna_adpcm *adpcm, uint16_t a) {
+  uint32_t a32 = a+1;
+  uint32_t ret = (adpcm->control2 & C2_8BIT) ? (a32<<6) : (a32<<3);
+  return ret-1;
+}
+
+static void adpcm_calc(struct opna_adpcm *adpcm) {
+  uint32_t step = (uint32_t)adpcm->step + (uint32_t)adpcm->delta;
+  adpcm->step = step & 0xffff;
+  if (step >> 16) {
+    if (adpcm->ramptr == addr_conv(adpcm, adpcm->limit)) {
+      adpcm->ramptr = 0;
+    }
+    if (adpcm->ramptr == addr_conv_e(adpcm, adpcm->end)) {
+      if (adpcm->control1 & C1_REPEAT) {
+        adpcm->ramptr = addr_conv(adpcm, adpcm->start);
+        adpcm->acc = 0;
+        adpcm->adpcmd = 127;
+        adpcm->prev_acc = 0;
+      } else {
+        // TODO: set EOS
+        adpcm->control1 = 0;
+        adpcm->out = 0;
+        adpcm->prev_acc = 0;
+      }
+    }
+    uint8_t data = 0;
+    if (adpcm->ram) {
+      data = adpcm->ram[(adpcm->ramptr>>1)&(OPNA_ADPCM_RAM_SIZE-1)];
+    }
+    if (adpcm->ramptr&1) {
+      data &= 0x0f;
+    } else {
+      data >>= 4;
+    }
+    adpcm->ramptr++;
+    adpcm->ramptr &= (1<<(24+1))-1;
+
+    adpcm->prev_acc = adpcm->acc;
+    int32_t acc_d = (((data&7)<<1)|1);
+    if (data&8) acc_d = -acc_d;
+    int32_t acc = adpcm->acc + (acc_d * adpcm->adpcmd / 8);
+    if (acc < -32768) acc = -32768;
+    if (acc > 32767) acc = 32767;
+    adpcm->acc = acc;
+
+    uint32_t adpcmd = (adpcm->adpcmd * adpcm_table[data&7] / 64);
+    if (adpcmd < 127) adpcmd = 127;
+    if (adpcmd > 24576) adpcmd = 24576;
+    adpcm->adpcmd = adpcmd;
+  }
+  int32_t out = (int32_t)adpcm->prev_acc * (0x10000-adpcm->step);
+  out += (int32_t)adpcm->acc * adpcm->step;
+  out >>= 16;
+  out *= adpcm->vol;
+  out >>= 8;
+  if (out < -32768) out = -32768;
+  if (out > 32767) out = 32767;
+  adpcm->out = out;
+}
+
+void opna_adpcm_writereg(struct opna_adpcm *adpcm, unsigned reg, unsigned val) {
+  val &= 0xff;
+  if (reg < 0x100) return;
+  if (reg >= 0x111) return;
+  reg &= 0xff;
+  switch (reg) {
+  case 0x00:
+    adpcm->control1 = val & C1_MASK;
+    if (adpcm->control1 & C1_START) {
+      adpcm->step = 0;
+      adpcm->acc = 0;
+      adpcm->prev_acc = 0;
+      adpcm->out = 0;
+      adpcm->adpcmd = 127;
+    }
+    if (adpcm->control1 & C1_MEMEXT) {
+      adpcm->ramptr = addr_conv(adpcm, adpcm->start);
+    }
+    if (adpcm->control1 & C1_RESET) {
+      adpcm->control1 = 0;
+      // TODO: set BRDY
+    }
+    break;
+  case 0x01:
+    adpcm->control2 = val & C2_MASK;
+    break;
+  case 0x02:
+    adpcm->start &= 0xff00;
+    adpcm->start |= val;
+    break;
+  case 0x03:
+    adpcm->start &= 0x00ff;
+    adpcm->start |= (val<<8);
+    break;
+  case 0x04:
+    adpcm->end &= 0xff00;
+    adpcm->end |= val;
+    break;
+  case 0x05:
+    adpcm->end &= 0x00ff;
+    adpcm->end |= (val<<8);
+    break;
+  case 0x08:
+    // data write
+    if ((adpcm->control1 & (C1_START|C1_REC|C1_MEMEXT)) == (C1_REC|C1_MEMEXT)) {
+      // external memory write
+      if (adpcm->ramptr != addr_conv_e(adpcm, adpcm->end)) {
+        if (adpcm->ram) {
+          adpcm->ram[(adpcm->ramptr>>1)&(OPNA_ADPCM_RAM_SIZE-1)] = val;
+        }
+        adpcm->ramptr += 2;
+      } else {
+        // TODO: set EOS
+      }
+    }
+    break;
+  case 0x09:
+    adpcm->delta &= 0xff00;
+    adpcm->delta |= val;
+    break;
+  case 0x0a:
+    adpcm->delta &= 0x00ff;
+    adpcm->delta |= (val<<8);
+    break;
+  case 0x0b:
+    adpcm->vol = val;
+    break;
+  case 0x0c:
+    adpcm->limit &= 0xff00;
+    adpcm->limit |= val;
+    break;
+  case 0x0d:
+    adpcm->limit &= 0x00ff;
+    adpcm->limit |= (val<<8);
+    break;
+  }
+}
+
+void opna_adpcm_mix(struct opna_adpcm *adpcm, int16_t *buf, unsigned samples) {
+  if (!adpcm->ram) return;
+  if (!(adpcm->control1 & C1_START)) return;
+  for (unsigned i = 0; i < samples; i++) {
+    adpcm_calc(adpcm);
+    int32_t lo = buf[i*2+0];
+    int32_t ro = buf[i*2+1];
+    if (adpcm->control2 & C2_L) lo += (adpcm->out>>1);
+    if (adpcm->control2 & C2_R) ro += (adpcm->out>>1);
+    if (lo < INT16_MIN) lo = INT16_MIN;
+    if (lo > INT16_MAX) lo = INT16_MAX;
+    if (ro < INT16_MIN) ro = INT16_MIN;
+    if (ro > INT16_MAX) ro = INT16_MAX;
+    buf[i*2+0] = lo;
+    buf[i*2+1] = ro;
+    if (!(adpcm->control1 & C1_START)) return;
+  }
+}
+
+void opna_adpcm_set_ram_256k(struct opna_adpcm *adpcm, void *ram) {
+  adpcm->ram = ram;
+}
+
+void *opna_adpcm_get_ram(struct opna_adpcm *adpcm) {
+  return adpcm->ram;
+}
-- 
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