32x: preliminary PWM implementation. 32x opts in menu

git-svn-id: file:///home/notaz/opt/svn/PicoDrive@790 be3aeb3a-fb24-0410-a615-afba39da0efa
2025-09-06 15:48:05 -04:00 · 2009-09-22 19:38:49 +00:00 · 2009-09-22 19:38:49 +00:00 · db1d3564e6
commit db1d3564e6
parent 5e128c6d27
16 changed files with 256 additions and 46 deletions
--- a/pico/32x/pwm.c
+++ b/pico/32x/pwm.c
@ -0,0 +1,144 @@
+#include "../pico_int.h"
+
+static int pwm_line_samples;
+static int pwm_cycles;
+static int pwm_mult;
+static int pwm_ptr;
+int pwm_frame_smp_cnt;
+
+
+void p32x_pwm_refresh(void)
+{
+  int cycles = Pico32x.regs[0x32 / 2];
+  int frame_samples;
+
+  cycles = (cycles - 1) & 0x0fff;
+  if (cycles < 500) {
+    elprintf(EL_32X|EL_ANOMALY, "pwm: low cycle value: %d", cycles + 1);
+    cycles = 500;
+  }
+  pwm_cycles = cycles;
+  pwm_mult = 0x10000 / cycles;
+  if (Pico.m.pal)
+    frame_samples = OSC_PAL / 7 * 3 / 50 / cycles;
+  else
+    frame_samples = OSC_NTSC / 7 * 3 / 60 / cycles;
+
+  pwm_line_samples = (frame_samples << 16) / scanlines_total;
+}
+
+// irq for every sample??
+// FIXME: we need to hit more than once per line :(
+void p32x_pwm_irq_check(void)
+{
+  int tm = (Pico32x.regs[0x30 / 2] & 0x0f00) >> 8;
+  if (tm == 0)
+    return; // TODO: verify
+
+  Pico32x.pwm_irq_sample_cnt += pwm_line_samples;
+  if (Pico32x.pwm_irq_sample_cnt >= (tm << 16)) {
+    Pico32x.pwm_irq_sample_cnt -= tm << 16;
+    Pico32x.sh2irqs |= P32XI_PWM;
+    p32x_update_irls();
+  }
+}
+
+unsigned int p32x_pwm_read16(unsigned int a)
+{
+  unsigned int d = 0;
+  int predict;
+
+  a &= 0x0e;
+  switch (a) {
+    case 0: // control
+    case 2: // cycle
+      return Pico32x.regs[(0x30 + a) / 2];
+
+    case 4: // L ch
+    case 6: // R ch
+    case 8: // MONO
+      predict = (pwm_line_samples * Pico.m.scanline) >> 16;
+      elprintf(EL_32X, "pwm: read status: ptr %d/%d, predict %d",
+        pwm_frame_smp_cnt, (pwm_line_samples * scanlines_total) >> 16, predict);
+      if (pwm_frame_smp_cnt > predict + 3)
+        d |= P32XP_FULL;
+      else if (pwm_frame_smp_cnt == 0 || pwm_frame_smp_cnt < predict - 1)
+        d |= P32XP_EMPTY;
+      break;
+  }
+
+  return d;
+}
+
+void p32x_pwm_write16(unsigned int a, unsigned int d)
+{
+  a &= 0x0e;
+  if (a == 0) // control
+    Pico32x.regs[0x30 / 2] = d;
+  else if (a == 2) { // cycle
+    Pico32x.regs[0x32 / 2] = d & 0x0fff;
+    p32x_pwm_refresh();
+    Pico32x.pwm_irq_sample_cnt = 0; // resets?
+  }
+  else if (a <= 8) {
+    d &= 0x0fff;
+    if (d > pwm_cycles)
+      d = pwm_cycles;
+    d = (d - pwm_cycles / 2) * pwm_mult;
+
+    if       (a < 6) // L ch
+      Pico32xMem->pwm[pwm_ptr * 2] = d;
+    else if (a == 6) // R ch
+      Pico32xMem->pwm[pwm_ptr * 2 + 1] = d;
+    else             // MONO
+      Pico32xMem->pwm[pwm_ptr * 2] = Pico32xMem->pwm[pwm_ptr * 2 + 1] = d;
+
+    if (a >= 6) { // R or MONO
+      pwm_frame_smp_cnt++;
+      pwm_ptr = (pwm_ptr + 1) & (PWM_BUFF_LEN - 1);
+        elprintf(EL_32X, "pwm: smp_cnt %d, ptr %d, smp %x", pwm_frame_smp_cnt, pwm_ptr, d);
+    }
+  }
+}
+
+void p32x_pwm_update(int *buf32, int length, int stereo)
+{
+  extern int pwm_ptr;
+  short *pwmb;
+  int step;
+  int p = 0;
+
+  if (pwm_ptr <= 16) // at least some samples..
+    return;
+
+  step = (pwm_ptr << 16) / length; // FIXME: division..
+  pwmb = Pico32xMem->pwm;
+
+  if (stereo)
+  {
+    while (length-- > 0) {
+      *buf32++ += pwmb[0];
+      *buf32++ += pwmb[1];
+
+      p += step;
+      pwmb += (p >> 16) * 2;
+      p &= 0xffff;
+    }
+  }
+  else
+  {
+    while (length-- > 0) {
+      *buf32++ += pwmb[0];
+
+      p += step;
+      pwmb += (p >> 16) * 2;
+      p &= 0xffff;
+    }
+  }
+
+  elprintf(EL_STATUS, "pwm_update: pwm_ptr %d, len %d, step %04x, done %d",
+    pwm_ptr, length, step, (pwmb - Pico32xMem->pwm) / 2);
+
+  pwm_ptr = 0;
+}
+