ref: 72f3156830b1458e856c0a5171a4042e62d3b8ac
parent: d110794e66d44f71191c74a10a079a1951a893a6
author: Sigrid Haflínudóttir <[email protected]>
date: Wed Feb 26 14:48:11 EST 2020
add AY-3-8190 WIP
--- /dev/null
+++ b/ay38910/README.md
@@ -1,0 +1,12 @@
+# ay38910
+
+AY-3-8910 as a filesystem, part of neindaw. WIP.
+
+This is a prototype built to achieve the following:
+
+ * figure out ways to deal with multi-voice/polyphony and mixing
+ * create a UDP-to-neindaw translation layer, a companion
+ app that allows using neindaw with [Orca](https://github.com/hundredrabbits/Orca).
+ * visualizing waveforms
+
+AY-3-8910 is emulated using (floooh/chips)[https://github.com/floooh/chips].
--- /dev/null
+++ b/ay38910/ay38910.c
@@ -1,0 +1,193 @@
+#include <u.h>
+#include <libc.h>
+#include <thread.h>
+#include <libsec.h>
+#include <draw.h>
+#include <keyboard.h>
+#define CHIPS_IMPL
+#define CHIPS_ASSERT assert
+#include "ay38910.h"
+
+#define MIN(a,b) ((a)<=(b)?(a):(b))
+#define MAX(a,b) ((a)>=(b)?(a):(b))
+
+enum {+ Tickhz = 2000000,
+
+ Levelenv = 1<<4,
+
+ Hold = 1<<0,
+ Alternate = 1<<1,
+ Attack = 1<<2,
+ Continue = 1<<3,
+};
+
+static void
+regw(ay38910_t *ay, int reg, int v)
+{+ u64int p;
+
+ /* latch address */
+ p = AY38910_BDIR | AY38910_BC1;
+ AY38910_SET_DATA(p, reg);
+ ay38910_iorq(ay, p);
+
+ /* write to psg */
+ p = AY38910_BDIR;
+ AY38910_SET_DATA(p, v);
+ ay38910_iorq(ay, p);
+
+ /* inactive */
+ ay38910_iorq(ay, 0);
+}
+
+static int
+regr(ay38910_t *ay, int reg)
+{+ u64int p;
+ int v;
+
+ /* latch address */
+ p = AY38910_BDIR | AY38910_BC1;
+ AY38910_SET_DATA(p, reg);
+ ay38910_iorq(ay, p);
+
+ /* read from psg */
+ v = AY38910_GET_DATA(ay38910_iorq(ay, AY38910_BC1));
+
+ /* inactive */
+ ay38910_iorq(ay, 0);
+
+ return v;
+}
+
+static int
+hz2tp(int hz)
+{+ return MAX(1, MIN(4095, Tickhz / (MAX(1, hz) * 16)));
+}
+
+static int
+hz2ep(int hz)
+{+ return MAX(1, MIN(65535, Tickhz / (MAX(1, hz) * 256)));
+}
+
+static int
+ms2ep(int ms)
+{+ return MAX(1, MIN(65535, (Tickhz / 1000) * ms / 256));
+}
+
+static void
+tone(ay38910_t *ay, int chan, int hz)
+{+ int tp;
+
+ tp = hz2tp(hz);
+ regw(ay, chan*2+0, tp & 0xff); /* fine */
+ regw(ay, chan*2+1, (tp>>8) & 0x0f); /* coarse */
+}
+
+static void
+toneon(ay38910_t *ay, int chan)
+{+ regw(ay, AY38910_REG_ENABLE, regr(ay, AY38910_REG_ENABLE) & ~(1<<chan));
+}
+
+static void
+toneoff(ay38910_t *ay, int chan)
+{+ regw(ay, AY38910_REG_ENABLE, regr(ay, AY38910_REG_ENABLE) | 1<<chan);
+}
+
+static void
+envp(ay38910_t *ay, int p)
+{+ regw(ay, AY38910_REG_ENV_PERIOD_FINE, p & 0xff);
+ regw(ay, AY38910_REG_ENV_PERIOD_COARSE, p>>8);
+}
+
+static void
+envsc(ay38910_t *ay, int v)
+{+ regw(ay, AY38910_REG_ENV_SHAPE_CYCLE, v & 0xf);
+}
+
+static void
+amp(ay38910_t *ay, int chan, int level)
+{+ regw(ay, AY38910_REG_AMP_A+chan, level);
+}
+
+static ay38910_t *
+aynew(float mag)
+{+ ay38910_desc_t d = {+ .type = AY38910_TYPE_8910,
+ .tick_hz = Tickhz,
+ .sound_hz = 44100,
+ .magnitude = mag,
+ };
+ ay38910_t *ay;
+
+ ay = malloc(sizeof(*ay));
+ ay38910_init(ay, &d);
+ regw(ay, AY38910_REG_ENABLE, 0xff); /* disable everything */
+
+ return ay;
+}
+
+void
+threadmain(int argc, char **argv)
+{+ u64int tick;
+ ay38910_t *ay[2];
+ int i, base, diff[] = {20, 200, 40, 220, 60};+ float f[2], x;
+ bool havesample[2];
+
+ USED(argc); USED(argv);
+
+ ay[0] = aynew(1.0);
+ amp(ay[0], 0, Levelenv | 4);
+ envp(ay[0], ms2ep(200));
+ envsc(ay[0], Continue|Alternate);
+ toneon(ay[0], 0);
+
+ ay[1] = aynew(1.0);
+ amp(ay[1], 0, Levelenv | 4);
+ envp(ay[1], ms2ep(500));
+ envsc(ay[1], Continue|Attack);
+ toneon(ay[1], 0);
+ tone(ay[1], 0, 500);
+
+ base = 200;
+ for (i = 0, tick = 0;; tick++) {+ /* 100Hz */
+ if ((tick % (Tickhz / 100)) == 0) {+ if (i >= nelem(diff))
+ i = 0;
+ tone(ay[0], 0, base+diff[i++]);
+ }
+
+ if (!havesample[0] && ay38910_tick(ay[0])) {+ f[0] = ay[0]->sample;
+ havesample[0] = true;
+ }
+ if (!havesample[1] && ay38910_tick(ay[1])) {+ f[1] = ay[1]->sample;
+ havesample[1] = true;
+ }
+ if (havesample[0] && havesample[1]) {+ havesample[0] = havesample[1] = false;
+ x = f[0] + f[1];
+ if (write(1, &x, sizeof(x)) < 0)
+ break;
+ }
+ }
+
+ free(ay[0]);
+ free(ay[1]);
+ threadexitsall(nil);
+}
--- /dev/null
+++ b/ay38910/ay38910.h
@@ -1,0 +1,598 @@
+#pragma once
+/*
+ ay38910.h -- AY-3-8910/2/3 sound chip emulator
+
+ Do this:
+ #define CHIPS_IMPL
+ before you include this file in *one* C or C++ file to create the
+ implementation.
+
+ Optionally provde the following macros with your own implementation
+
+ CHIPS_ASSERT(c) -- your own assert macro (default: assert(c))
+
+ EMULATED PINS:
+
+ +-----------+
+ BC1 -->| |<-> DA0
+ BDIR -->| |...
+ | |<-> DA7
+ | |
+ | |<-> (IOA0)
+ | |...
+ | |<-> (IOA7)
+ | |
+ | |<-> (IOB0)
+ | |...
+ | |<-> (IOB7)
+ +-----------+
+
+ NOT EMULATED:
+
+ - the BC2 pin is ignored since it makes only sense when connected to
+ a CP1610 CPU
+ - the RESET pin state is ignored, instead call ay38910_reset()
+
+ ## zlib/libpng license
+
+ Copyright (c) 2018 Andre Weissflog
+ This software is provided 'as-is', without any express or implied warranty.
+ In no event will the authors be held liable for any damages arising from the
+ use of this software.
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute it
+ freely, subject to the following restrictions:
+ 1. The origin of this software must not be misrepresented; you must not
+ claim that you wrote the original software. If you use this software in a
+ product, an acknowledgment in the product documentation would be
+ appreciated but is not required.
+ 2. Altered source versions must be plainly marked as such, and must not
+ be misrepresented as being the original software.
+ 3. This notice may not be removed or altered from any source
+ distribution.
+*/
+#include <stdint.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {+#endif
+
+/*
+ Pin definitions.
+
+ Note that the BC2 is not emulated since it is usually always
+ set to active when not connected to a CP1610 processor. The
+ remaining BDIR and BC1 pins are interpreted as follows:
+
+ |BDIR|BC1|
+ +----+---+
+ | 0 | 0 | INACTIVE
+ | 0 | 1 | READ FROM PSG
+ | 1 | 0 | WRITE TO PSG
+ | 1 | 1 | LATCH ADDRESS
+*/
+
+/* 8 bits data/address bus shared with CPU data bus */
+#define AY38910_DA0 (1ULL<<16)
+#define AY38910_DA1 (1ULL<<17)
+#define AY38910_DA2 (1ULL<<18)
+#define AY38910_DA3 (1ULL<<19)
+#define AY38910_DA4 (1ULL<<20)
+#define AY38910_DA5 (1ULL<<21)
+#define AY38910_DA6 (1ULL<<22)
+#define AY38910_DA7 (1ULL<<23)
+
+/* reset pin shared with CPU */
+#define AY38910_RESET (1ULL<<34)
+
+/* chip-specific pins start at position 44 */
+#define AY38910_BDIR (1ULL<<40)
+#define AY38910_BC1 (1ULL<<41)
+
+/* IO port pins */
+#define AY38910_IOA0 (1ULL<<48)
+#define AY38910_IOA1 (1ULL<<49)
+#define AY38910_IOA2 (1ULL<<50)
+#define AY38910_IOA3 (1ULL<<51)
+#define AY38910_IOA4 (1ULL<<52)
+#define AY38910_IOA5 (1ULL<<53)
+#define AY38910_IOA6 (1ULL<<54)
+#define AY38910_IOA7 (1ULL<<55)
+
+#define AY38910_IOB0 (1ULL<<56)
+#define AY38910_IOB1 (1ULL<<57)
+#define AY38910_IOB2 (1ULL<<58)
+#define AY38910_IOB3 (1ULL<<59)
+#define AY38910_IOB4 (1ULL<<60)
+#define AY38910_IOB5 (1ULL<<61)
+#define AY38910_IOB6 (1ULL<<62)
+#define AY38910_IOB7 (1ULL<<63)
+
+/* AY-3-8910 registers */
+#define AY38910_REG_PERIOD_A_FINE (0)
+#define AY38910_REG_PERIOD_A_COARSE (1)
+#define AY38910_REG_PERIOD_B_FINE (2)
+#define AY38910_REG_PERIOD_B_COARSE (3)
+#define AY38910_REG_PERIOD_C_FINE (4)
+#define AY38910_REG_PERIOD_C_COARSE (5)
+#define AY38910_REG_PERIOD_NOISE (6)
+#define AY38910_REG_ENABLE (7)
+#define AY38910_REG_AMP_A (8)
+#define AY38910_REG_AMP_B (9)
+#define AY38910_REG_AMP_C (10)
+#define AY38910_REG_ENV_PERIOD_FINE (11)
+#define AY38910_REG_ENV_PERIOD_COARSE (12)
+#define AY38910_REG_ENV_SHAPE_CYCLE (13)
+#define AY38910_REG_IO_PORT_A (14) /* not on AY-3-8913 */
+#define AY38910_REG_IO_PORT_B (15) /* not on AY-3-8912/3 */
+/* number of registers */
+#define AY38910_NUM_REGISTERS (16)
+/* error-accumulation precision boost */
+#define AY38910_FIXEDPOINT_SCALE (16)
+/* number of channels */
+#define AY38910_NUM_CHANNELS (3)
+/* DC adjustment buffer length */
+#define AY38910_DCADJ_BUFLEN (512)
+
+/* IO port names */
+#define AY38910_PORT_A (0)
+#define AY38910_PORT_B (1)
+
+/* envelope shape bits */
+#define AY38910_ENV_HOLD (1<<0)
+#define AY38910_ENV_ALTERNATE (1<<1)
+#define AY38910_ENV_ATTACK (1<<2)
+#define AY38910_ENV_CONTINUE (1<<3)
+
+/* callbacks for input/output on I/O ports */
+typedef uint8_t (*ay38910_in_t)(int port_id, void* user_data);
+typedef void (*ay38910_out_t)(int port_id, uint8_t data, void* user_data);
+
+/* chip subtypes */
+typedef enum {+ AY38910_TYPE_8910 = 0,
+ AY38910_TYPE_8912,
+ AY38910_TYPE_8913
+} ay38910_type_t;
+
+/* setup parameters for ay38910_init() call */
+typedef struct {+ ay38910_type_t type; /* the subtype (default 0 is AY-3-8910) */
+ int tick_hz; /* frequency at which ay38910_tick() will be called in Hz */
+ int sound_hz; /* number of samples that will be produced per second */
+ float magnitude; /* output sample magnitude, from 0.0 (silence) to 1.0 (max volume) */
+ ay38910_in_t in_cb; /* I/O port input callback */
+ ay38910_out_t out_cb; /* I/O port output callback */
+ void* user_data; /* optional user-data for callbacks */
+} ay38910_desc_t;
+
+/* a tone channel */
+typedef struct {+ uint16_t period;
+ uint16_t counter;
+ uint32_t bit;
+ uint32_t tone_disable;
+ uint32_t noise_disable;
+} ay38910_tone_t;
+
+/* the noise channel state */
+typedef struct {+ uint16_t period;
+ uint16_t counter;
+ uint32_t rng;
+ uint32_t bit;
+} ay38910_noise_t;
+
+/* the envelope generator */
+typedef struct {+ uint16_t period;
+ uint16_t counter;
+ bool shape_holding;
+ bool shape_hold;
+ uint8_t shape_counter;
+ uint8_t shape_state;
+} ay38910_env_t;
+
+/* AY-3-8910 state */
+typedef struct {+ ay38910_type_t type; /* the chip flavour */
+ ay38910_in_t in_cb; /* the port-input callback */
+ ay38910_out_t out_cb; /* the port-output callback */
+ void* user_data; /* optional user-data for callbacks */
+ uint32_t tick; /* a tick counter for internal clock division */
+ uint8_t addr; /* 4-bit address latch */
+ union { /* the register bank */+ uint8_t reg[AY38910_NUM_REGISTERS];
+ struct {+ uint8_t period_a_fine;
+ uint8_t period_a_coarse;
+ uint8_t period_b_fine;
+ uint8_t period_b_coarse;
+ uint8_t period_c_fine;
+ uint8_t period_c_coarse;
+ uint8_t period_noise;
+ uint8_t enable;
+ uint8_t amp_a;
+ uint8_t amp_b;
+ uint8_t amp_c;
+ uint8_t period_env_fine;
+ uint8_t period_env_coarse;
+ uint8_t env_shape_cycle;
+ uint8_t port_a;
+ uint8_t port_b;
+ };
+ };
+ ay38910_tone_t tone[AY38910_NUM_CHANNELS]; /* the 3 tone channels */
+ ay38910_noise_t noise; /* the noise generator state */
+ ay38910_env_t env; /* the envelope generator state */
+ uint64_t pins; /* last pin state for debug inspection */
+
+ /* sample generation state */
+ int sample_period;
+ int sample_counter;
+ float mag;
+ float sample;
+ float dcadj_sum;
+ uint32_t dcadj_pos;
+ float dcadj_buf[AY38910_DCADJ_BUFLEN];
+} ay38910_t;
+
+/* extract 8-bit data bus from 64-bit pins */
+#define AY38910_GET_DATA(p) ((uint8_t)(p>>16))
+/* merge 8-bit data bus value into 64-bit pins */
+#define AY38910_SET_DATA(p,d) {p=((p&~0xFF0000)|((d&0xFF)<<16));}+/* set 8-bit port A data on 64-bit pin mask */
+#define AY38910_SET_PA(p,d) {p=((p&~0x00FF000000000000ULL)|((((uint64_t)d)&0xFFULL)<<48));}+/* set 8-bit port B data on 64-bit pin mask */
+#define AY38910_SET_PB(p,d) {p=((p&~0xFF00000000000000ULL)|((((uint64_t)d)&0xFFULL)<<56));}+
+/* initialize a AY-3-8910 instance */
+void ay38910_init(ay38910_t* ay, const ay38910_desc_t* desc);
+/* reset an existing AY-3-8910 instance */
+void ay38910_reset(ay38910_t* ay);
+/* perform an IO request machine cycle */
+uint64_t ay38910_iorq(ay38910_t* ay, uint64_t pins);
+/* tick the AY-3-8910, return true if a new sample is ready */
+bool ay38910_tick(ay38910_t* ay);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+/*-- IMPLEMENTATION ----------------------------------------------------------*/
+#ifdef CHIPS_IMPL
+#include <string.h>
+#ifndef CHIPS_ASSERT
+ #include <assert.h>
+ #define CHIPS_ASSERT(c) assert(c)
+#endif
+
+/* extract 8-bit data bus from 64-bit pins */
+#define AY38910_DATA(p) ((uint8_t)(p>>16))
+/* merge 8-bit data bus value into 64-bit pins */
+#define AY38910_SET_DATA(p,d) {p=((p&~0xFF0000)|((d&0xFF)<<16));}+
+/* valid register content bitmasks */
+static const uint8_t _ay38910_reg_mask[AY38910_NUM_REGISTERS] = {+ 0xFF, /* AY38910_REG_PERIOD_A_FINE */
+ 0x0F, /* AY38910_REG_PERIOD_A_COARSE */
+ 0xFF, /* AY38910_REG_PERIOD_B_FINE */
+ 0x0F, /* AY38910_REG_PERIOD_B_COARSE */
+ 0xFF, /* AY38910_REG_PERIOD_C_FINE */
+ 0x0F, /* AY38910_REG_PERIOD_C_COARSE */
+ 0x1F, /* AY38910_REG_PERIOD_NOISE */
+ 0xFF, /* AY38910_REG_ENABLE */
+ 0x1F, /* AY38910_REG_AMP_A (0..3: 4-bit volume, 4: use envelope) */
+ 0x1F, /* AY38910_REG_AMP_B (0..3: 4-bit volume, 4: use envelope) */
+ 0x1F, /* AY38910_REG_AMP_C (0..3: 4-bit volume, 4: use envelope) */
+ 0xFF, /* AY38910_REG_ENV_PERIOD_FINE */
+ 0xFF, /* AY38910_REG_ENV_PERIOD_COARSE */
+ 0x0F, /* AY38910_REG_ENV_SHAPE_CYCLE */
+ 0xFF, /* AY38910_REG_IO_PORT_A */
+ 0xFF, /* AY38910_REG_IO_PORT_B */
+};
+
+/* volume table from: https://github.com/true-grue/ayumi/blob/master/ayumi.c */
+static const float _ay38910_volumes[16] = {+ 0.0f,
+ 0.00999465934234f,
+ 0.0144502937362f,
+ 0.0210574502174f,
+ 0.0307011520562f,
+ 0.0455481803616f,
+ 0.0644998855573f,
+ 0.107362478065f,
+ 0.126588845655f,
+ 0.20498970016f,
+ 0.292210269322f,
+ 0.372838941024f,
+ 0.492530708782f,
+ 0.635324635691f,
+ 0.805584802014f,
+ 1.0f
+};
+
+/* canned envelope generator shapes */
+static const uint8_t _ay38910_shapes[16][32] = {+ /* CONTINUE ATTACK ALTERNATE HOLD */
+ /* 0 0 X X */
+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ /* 0 1 X X */
+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ /* 1 0 0 0 */
+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 },+ /* 1 0 0 1 */
+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+ /* 1 0 1 0 */
+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },+ /* 1 0 1 1 */
+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15 },+ /* 1 1 0 0 */
+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },+ /* 1 1 0 1 */
+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15 },+ /* 1 1 1 0 */
+ { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 },+ /* 1 1 1 1 */
+ { 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },+};
+
+/* DC adjustment filter from StSound, this moves an "offcenter"
+ signal back to the zero-line (e.g. the volume-level output
+ from the chip simulation which is >0.0 gets converted to
+ a +/- sample value)
+*/
+static float _ay38910_dcadjust(ay38910_t* ay, float s) {+ ay->dcadj_sum -= ay->dcadj_buf[ay->dcadj_pos];
+ ay->dcadj_sum += s;
+ ay->dcadj_buf[ay->dcadj_pos] = s;
+ ay->dcadj_pos = (ay->dcadj_pos + 1) & (AY38910_DCADJ_BUFLEN-1);
+ return s - (ay->dcadj_sum / AY38910_DCADJ_BUFLEN);
+}
+
+/* update computed values after registers have been reprogrammed */
+static void _ay38910_update_values(ay38910_t* ay) {+ for (int i = 0; i < AY38910_NUM_CHANNELS; i++) {+ ay38910_tone_t* chn = &ay->tone[i];
+ /* "...Note also that due to the design technique used in the Tone Period
+ count-down, the lowest period value is 000000000001 (divide by 1)
+ and the highest period value is 111111111111 (divide by 4095)
+ */
+ chn->period = (ay->reg[2*i+1]<<8)|(ay->reg[2*i]);
+ if (0 == chn->period) {+ chn->period = 1;
+ }
+ /* a set 'enable bit' actually means 'disabled' */
+ chn->tone_disable = (ay->enable>>i) & 1;
+ chn->noise_disable = (ay->enable>>(3+i)) & 1;
+ }
+ /* noise generator values */
+ ay->noise.period = ay->period_noise;
+ if (ay->noise.period == 0) {+ ay->noise.period = 1;
+ }
+ /* envelope generator values */
+ ay->env.period = (ay->period_env_coarse<<8)|ay->period_env_fine;
+ if (ay->env.period == 0) {+ ay->env.period = 1;
+ }
+}
+
+/* reset the env shape generator, only called when env-shape register is updated */
+static void _ay38910_restart_env_shape(ay38910_t* ay) {+ ay->env.shape_holding = false;
+ ay->env.shape_counter = 0;
+ if (!(ay->env_shape_cycle & AY38910_ENV_CONTINUE) || (ay->env_shape_cycle & AY38910_ENV_HOLD)) {+ ay->env.shape_hold = true;
+ }
+ else {+ ay->env.shape_hold = false;
+ }
+}
+
+void ay38910_init(ay38910_t* ay, const ay38910_desc_t* desc) {+ CHIPS_ASSERT(ay && desc);
+ CHIPS_ASSERT(desc->tick_hz > 0);
+ CHIPS_ASSERT(desc->sound_hz > 0);
+ memset(ay, 0, sizeof(*ay));
+ /* note: input and output callbacks are optional */
+ ay->in_cb = desc->in_cb;
+ ay->out_cb = desc->out_cb;
+ ay->user_data = desc->user_data;
+ ay->type = desc->type;
+ ay->noise.rng = 1;
+ ay->sample_period = (desc->tick_hz * AY38910_FIXEDPOINT_SCALE) / desc->sound_hz;
+ ay->sample_counter = ay->sample_period;
+ ay->mag = desc->magnitude;
+ _ay38910_update_values(ay);
+ _ay38910_restart_env_shape(ay);
+}
+
+void ay38910_reset(ay38910_t* ay) {+ CHIPS_ASSERT(ay);
+ ay->addr = 0;
+ ay->tick = 0;
+ for (int i = 0; i < AY38910_NUM_REGISTERS; i++) {+ ay->reg[i] = 0;
+ }
+ _ay38910_update_values(ay);
+ _ay38910_restart_env_shape(ay);
+}
+
+bool ay38910_tick(ay38910_t* ay) {+ ay->tick++;
+ if ((ay->tick & 7) == 0) {+ /* tick the tone channels */
+ for (int i = 0; i < AY38910_NUM_CHANNELS; i++) {+ ay38910_tone_t* chn = &ay->tone[i];
+ if (++chn->counter >= chn->period) {+ chn->counter = 0;
+ chn->bit ^= 1;
+ }
+ }
+
+ /* tick the noise channel */
+ if (++ay->noise.counter >= ay->noise.period) {+ ay->noise.counter = 0;
+ ay->noise.bit ^= 1;
+ if (ay->noise.bit) {+ // random number generator from MAME:
+ // https://github.com/mamedev/mame/blob/master/src/devices/sound/ay8910.cpp
+ // The Random Number Generator of the 8910 is a 17-bit shift
+ // register. The input to the shift register is bit0 XOR bit3
+ // (bit0 is the output). This was verified on AY-3-8910 and YM2149 chips.
+ ay->noise.rng ^= (((ay->noise.rng & 1) ^ ((ay->noise.rng >> 3) & 1)) << 17);
+ ay->noise.rng >>= 1;
+ }
+ }
+ }
+
+ /* tick the envelope generator */
+ if ((ay->tick & 15) == 0) {+ if (++ay->env.counter >= ay->env.period) {+ ay->env.counter = 0;
+ if (!ay->env.shape_holding) {+ ay->env.shape_counter = (ay->env.shape_counter + 1) & 0x1F;
+ if (ay->env.shape_hold && (0x1F == ay->env.shape_counter)) {+ ay->env.shape_holding = true;
+ }
+ }
+ ay->env.shape_state = _ay38910_shapes[ay->env_shape_cycle][ay->env.shape_counter];
+ }
+ }
+
+ /* generate new sample? */
+ ay->sample_counter -= AY38910_FIXEDPOINT_SCALE;
+ if (ay->sample_counter <= 0) {+ ay->sample_counter += ay->sample_period;
+ float sm = 0.0f;
+ for (int i = 0; i < AY38910_NUM_CHANNELS; i++) {+ const ay38910_tone_t* chn = &ay->tone[i];
+ float vol;
+ if (0 == (ay->reg[AY38910_REG_AMP_A+i] & (1<<4))) {+ /* fixed amplitude */
+ vol = _ay38910_volumes[ay->reg[AY38910_REG_AMP_A+i] & 0x0F];
+ }
+ else {+ /* envelope control */
+ vol = _ay38910_volumes[ay->env.shape_state];
+ }
+ int vol_enable = (chn->bit|chn->tone_disable) & ((ay->noise.rng&1)|(chn->noise_disable));
+ if (vol_enable) {+ sm += vol;
+ }
+ }
+ ay->sample = _ay38910_dcadjust(ay, sm) * ay->mag;
+ return true; /* new sample is ready */
+ }
+ /* fallthrough: no new sample ready yet */
+ return false;
+}
+
+uint64_t ay38910_iorq(ay38910_t* ay, uint64_t pins) {+ if (pins & (AY38910_BDIR|AY38910_BC1)) {+ if (pins & AY38910_BDIR) {+ const uint8_t data = AY38910_DATA(pins);
+ if (pins & AY38910_BC1) {+ /* latch address */
+ ay->addr = data;
+ }
+ else {+ /* Write to register using the currently latched address.
+ The whole 8-bit address is considered, the low 4 bits
+ are the register index, and the upper bits are burned
+ into the chip as a 'chip select' and are usually 0
+ (this emulator assumes they are 0, so addresses greater
+ are ignored for reading and writing)
+ */
+ if (ay->addr < AY38910_NUM_REGISTERS) {+ /* write register content, and update dependent values */
+ ay->reg[ay->addr] = data & _ay38910_reg_mask[ay->addr];
+ _ay38910_update_values(ay);
+ if (ay->addr == AY38910_REG_ENV_SHAPE_CYCLE) {+ _ay38910_restart_env_shape(ay);
+ }
+ /* Handle port output:
+
+ If port A or B is in output mode, call the
+ port output callback to notify the outer world
+ about the new register value.
+
+ input/output mode is defined by bits 6 and 7 of
+ the 'enable' register
+ bit6 = 1: port A in output mode
+ bit7 = 1: port B in output mode
+ */
+ else if (ay->addr == AY38910_REG_IO_PORT_A) {+ if (ay->enable & (1<<6)) {+ if (ay->out_cb) {+ ay->out_cb(AY38910_PORT_A, ay->port_a, ay->user_data);
+ }
+ }
+ }
+ else if (ay->addr == AY38910_REG_IO_PORT_B) {+ if (ay->enable & (1<<7)) {+ if (ay->out_cb) {+ ay->out_cb(AY38910_PORT_B, ay->port_b, ay->user_data);
+ }
+ }
+ }
+ }
+ }
+ }
+ else {+ /* Read from register using the currently latched address.
+ See 'write' for why the latched address must be in the
+ valid register range to have an effect.
+ */
+ if (ay->addr < AY38910_NUM_REGISTERS) {+ /* Handle port input:
+
+ If port A or B is in input mode, first call the port
+ input callback to update the port register content.
+
+ input/output mode is defined by bits 6 and 7 of
+ the 'enable' register:
+ bit6 = 0: port A in input mode
+ bit7 = 0: port B in input mode
+ */
+ if (ay->addr == AY38910_REG_IO_PORT_A) {+ if ((ay->enable & (1<<6)) == 0) {+ if (ay->in_cb) {+ ay->port_a = ay->in_cb(AY38910_PORT_A, ay->user_data);
+ }
+ else {+ ay->port_a = 0xFF;
+ }
+ }
+ }
+ else if (ay->addr == AY38910_REG_IO_PORT_B) {+ if ((ay->enable & (1<<7)) == 0) {+ if (ay->in_cb) {+ ay->port_b = ay->in_cb(AY38910_PORT_B, ay->user_data);
+ }
+ else {+ ay->port_b = 0xFF;
+ }
+ }
+ }
+ /* read register content into data pins */
+ const uint8_t data = ay->reg[ay->addr];
+ AY38910_SET_DATA(pins, data);
+ }
+ }
+ AY38910_SET_PA(pins, ay->port_a);
+ AY38910_SET_PB(pins, ay->port_b);
+ ay->pins = pins;
+ }
+ return pins;
+}
+
+#endif /* CHIPS_IMPL */
--- /dev/null
+++ b/ay38910/mkfile
@@ -1,0 +1,18 @@
+</$objtype/mkfile
+
+TARG=ay38910
+CFLAGS=$CFLAGS -p
+BIN=/$objtype/bin/audio
+MAN=/sys/man/1
+
+HFILES=\
+ ay38910.h\
+
+OFILES=\
+ ay38910.$O\
+
+default:V: all
+
+</sys/src/cmd/mkone
+
+install:V: $MAN/$TARG
--- /dev/null
+++ b/ay38910/stdbool.h
@@ -1,0 +1,1 @@
+typedef enum { false, true } bool;--- /dev/null
+++ b/ay38910/stdint.h
@@ -1,0 +1,4 @@
+typedef u8int uint8_t;
+typedef u16int uint16_t;
+typedef u32int uint32_t;
+typedef u64int uint64_t;