32x DMA memory copy performance optimisation

cpu/sh2/compiler.c

@@ -2261,7 +2261,7 @@ static int emit_get_rom_data(SH2 *sh2, sh2_reg_e r, u32 offs, int size, u32 *val
   if (gconst_get(r, &a)) {
     a += offs;
     // check if rom is memory mapped (not bank switched), and address is in rom
-    if (dr_is_rom(a) && p32x_sh2_get_mem_ptr(a, &mask, sh2)) {
+    if (dr_is_rom(a) && p32x_sh2_get_mem_ptr(a, &mask, sh2) != (void *)-1) {
       switch (size & MF_SIZEMASK) {
       case 0:   *val = (s8)p32x_sh2_read8(a, sh2s);   break;  // 8
       case 1:   *val = (s16)p32x_sh2_read16(a, sh2s); break;  // 16
@@ -4896,12 +4896,7 @@ void sh2_drc_flush_all(void)
 
 void sh2_drc_mem_setup(SH2 *sh2)
 {
-  // fill the convenience pointers
+  // fill the DRC-only convenience pointers
-  sh2->p_bios = sh2->is_slave ? Pico32xMem->sh2_rom_s.w : Pico32xMem->sh2_rom_m.w;
-  sh2->p_da = sh2->data_array;
-  sh2->p_sdram = Pico32xMem->sdram;
-  sh2->p_rom = Pico.rom;
-  // sh2->p_dram filled in dram bank switching
   sh2->p_drcblk_da = Pico32xMem->drcblk_da[!!sh2->is_slave];
   sh2->p_drcblk_ram = Pico32xMem->drcblk_ram;
 }

pico/32x/memory.c

@@ -1855,17 +1855,15 @@ void *p32x_sh2_get_mem_ptr(u32 a, u32 *mask, SH2 *sh2)
 {
   const sh2_memmap *mm = sh2->read8_map;
   void *ret = (void *)-1;
-  u32 am;
 
-  mm += a >> SH2_READ_SHIFT;
+  mm += SH2MAP_ADDR2OFFS_R(a);
-  am = a & ((1 << SH2_READ_SHIFT)-1);
+  if (!map_flag_set(mm->addr)) {
-  if (!map_flag_set(mm->addr) && !(am & ~mm->mask)) {
     // directly mapped memory (SDRAM, ROM, data array)
     ret = (void *)(mm->addr << 1);
     *mask = mm->mask;
   } else if ((a & ~0x7ff) == 0) {
     // BIOS, has handler function since it shares its segment with I/O
-    ret = sh2->is_slave ? Pico32xMem->sh2_rom_s.w : Pico32xMem->sh2_rom_m.w;
+    ret = sh2->p_bios;
     *mask = 0x7ff;
   } else if ((a & 0xc6000000) == 0x02000000) {
     // banked ROM. Return bank address
@@ -1877,6 +1875,75 @@ void *p32x_sh2_get_mem_ptr(u32 a, u32 *mask, SH2 *sh2)
   return ret;
 }
 
+int p32x_sh2_memcpy(u32 dst, u32 src, int count, int size, SH2 *sh2)
+{
+  u32 mask;
+  void *ps, *pd;
+  int len, i;
+
+  // check if src and dst points to memory (rom/sdram/dram/da)
+  if ((pd = p32x_sh2_get_mem_ptr(dst, &mask, sh2)) == (void *)-1)
+    return 0;
+  if ((ps = p32x_sh2_get_mem_ptr(src, &mask, sh2)) == (void *)-1)
+    return 0;
+  ps += src & mask;
+  len = count * size;
+
+  // DRAM in byte access is always in overwrite mode
+  if (pd == sh2->p_dram && size == 1)
+    dst |= 0x20000;
+
+  // align dst to halfword
+  if (dst & 1) {
+    p32x_sh2_write8(dst, *(u8 *)((uptr)ps ^ 1), sh2);
+    ps++, dst++, len --;
+  }
+
+  // copy data
+  if ((uptr)ps & 1) {
+    // unaligned, use halfword copy mode to reduce memory bandwidth
+    u16 *sp = (u16 *)(ps - 1);
+    u16 dl, dh = *sp++;
+    for (i = 0; i < (len & ~1); i += 2, dst += 2, sp++) {
+      dl = dh, dh = *sp;
+      p32x_sh2_write16(dst, (dh >> 8) | (dl << 8), sh2);
+    }
+    if (len & 1)
+      p32x_sh2_write8(dst, dh, sh2);
+  } else {
+    // dst and src at least halfword aligned
+    u16 *sp = (u16 *)ps;
+    // align dst to word
+    if ((dst & 2) && len >= 2) {
+      p32x_sh2_write16(dst, *sp++, sh2);
+      dst += 2, len -= 2;
+    }
+    if ((uptr)sp & 2) {
+      // halfword copy, using word writes to reduce memory bandwidth
+      u16 dl, dh;
+      for (i = 0; i < (len & ~3); i += 4, dst += 4, sp += 2) {
+        dl = sp[0], dh = sp[1];
+        p32x_sh2_write32(dst, (dl << 16) | dh, sh2);
+      }
+    } else {
+      // word copy
+      u32 d;
+      for (i = 0; i < (len & ~3); i += 4, dst += 4, sp += 2) {
+        d = *(u32 *)sp;
+        p32x_sh2_write32(dst, (d << 16) | (d >> 16), sh2);
+      }
+    }
+    if (len & 2) {
+      p32x_sh2_write16(dst, *sp++, sh2);
+      dst += 2;
+    }
+    if (len & 1)
+      p32x_sh2_write8(dst, *sp >> 8, sh2);
+  }
+
+  return count;
+}
+
 // -----------------------------------------------------------------
 
 static void z80_md_bank_write_32x(unsigned int a, unsigned char d)
@@ -2107,8 +2174,12 @@ void Pico32xSwapDRAM(int b)
   ssh2_read16_map[0x04/2].addr = ssh2_read16_map[0x24/2].addr =
   ssh2_read32_map[0x04/2].addr = ssh2_read32_map[0x24/2].addr = MAP_MEMORY(Pico32xMem->dram[b]);
 
-  msh2.p_dram = ssh2.p_dram = Pico32xMem->dram[b]; // DRC conveniance ptr
+  // convenience ptrs
-  msh2.p_rom  = ssh2.p_rom  = Pico.rom;
+  msh2.p_sdram = ssh2.p_sdram = Pico32xMem->sdram;
+  msh2.p_dram  = ssh2.p_dram  = Pico32xMem->dram[b];
+  msh2.p_rom   = ssh2.p_rom   = Pico.rom;
+  msh2.p_bios  = Pico32xMem->sh2_rom_m.w; msh2.p_da = msh2.data_array;
+  ssh2.p_bios  = Pico32xMem->sh2_rom_s.w; ssh2.p_da = ssh2.data_array;
 }
 
 static void bank_switch_rom_sh2(void)

pico/32x/sh2soc.c

@@ -129,6 +129,24 @@ static void dmac_transfer_one(SH2 *sh2, struct dma_chan *chan)
     chan->sar += size;
 }
 
+// optimization for copying around memory with SH2 DMA
+static void dmac_memcpy(struct dma_chan *chan, SH2 *sh2)
+{
+  u32 size = (chan->chcr >> 10) & 3, up = chan->chcr & (1 << 14);
+  int count;
+
+  if (!up || chan->tcr < 4)
+    return;
+  if (size == 3) size = 2;  // 4-word xfer mode still counts in words
+  // XXX check TCR being a multiple of 4 in 4-word xfer mode?
+  // XXX check alignment of sar/dar, generating a bus error if unaligned?
+  count = p32x_sh2_memcpy(chan->dar, chan->sar, chan->tcr, 1 << size, sh2);
+
+  chan->sar += count << size;
+  chan->dar += count << size;
+  chan->tcr -= count;
+}
+
 // DMA trigger by SH2 register write
 static void dmac_trigger(SH2 *sh2, struct dma_chan *chan)
 {
@@ -139,6 +157,11 @@ static void dmac_trigger(SH2 *sh2, struct dma_chan *chan)
   if (chan->chcr & DMA_AR) {
     // auto-request transfer
     sh2->state |= SH2_STATE_SLEEP;
+    if ((((chan->chcr >> 12) ^ (chan->chcr >> 14)) & 3) == 0 &&
+        (((chan->chcr >> 14) ^ (chan->chcr >> 15)) & 1) == 1) {
+      // SM == DM and either DM0 or DM1 are set. check for mem to mem copy
+      dmac_memcpy(chan, sh2);
+    }
     while ((int)chan->tcr > 0)
       dmac_transfer_one(sh2, chan);
     dmac_transfer_complete(sh2, chan);

pico/pico_int.h

@@ -937,6 +937,7 @@ unsigned int REGPARM(3) p32x_sh2_poll_memory16(unsigned int a, unsigned int d, S
 unsigned int REGPARM(3) p32x_sh2_poll_memory32(unsigned int a, unsigned int d, SH2 *sh2);
 void *p32x_sh2_get_mem_ptr(unsigned int a, unsigned int *mask, SH2 *sh2);
 void p32x_sh2_poll_event(SH2 *sh2, unsigned int flags, unsigned int m68k_cycles);
+int p32x_sh2_memcpy(unsigned int dst, unsigned int src, int count, int size, SH2 *sh2);
 
 // 32x/draw.c
 void PicoDrawSetOutFormat32x(pdso_t which, int use_32x_line_mode);

tools/mkoffsets.sh

@@ -89,7 +89,7 @@ get_define OFS_PMEM32x_ Pico32xMem pal_native	; echo "$line" >>$fn
 get_define OFS_SH2_ SH2_ is_slave		; echo "$line" >>$fn
 get_define OFS_SH2_ SH2_ p_bios			; echo "$line" >>$fn
 get_define OFS_SH2_ SH2_ p_da			; echo "$line" >>$fn
-get_define OFS_SH2_ SH2_ p_sdram			; echo "$line" >>$fn
+get_define OFS_SH2_ SH2_ p_sdram		; echo "$line" >>$fn
 get_define OFS_SH2_ SH2_ p_rom			; echo "$line" >>$fn
 get_define OFS_SH2_ SH2_ p_dram			; echo "$line" >>$fn
 get_define OFS_SH2_ SH2_ p_drcblk_da		; echo "$line" >>$fn