--- /dev/null
+/*
+ Implementation of DMA routines on DOS
+ Copyright (C) 1999 by Andrew Zabolotny, <bit@eltech.ru>
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public
+ License as published by the Free Software Foundation; either
+ version 2 of the License, or (at your option) any later version.
+
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with this library; if not, write to the Free
+ Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "dosdma.h"
+
+#include <go32.h> /* includes sys/version.h (djgpp >= 2.02) */
+#include <dos.h>
+#include <dpmi.h>
+#include <sys/nearptr.h>
+#include <malloc.h>
+#include "mikmod.h" /* for MikMod_malloc() & co */
+
+/* BUG WARNING: there is an error in DJGPP libraries <= 2.01:
+ * src/libc/dpmi/api/d0102.s loads the selector and allocsize
+ * arguments in the wrong order. DJGPP >= 2.02 have it fixed. */
+#if (!defined(__DJGPP_MINOR__) || (__DJGPP_MINOR__+0) < 2)
+#warning __dpmi_resize_dos_memory() from DJGPP <= 2.01 is broken!
+#endif
+
+__dma_regs dma[8] = {
+/* *INDENT-OFF* */
+ {DMA_ADDR_0, DMA_PAGE_0, DMA_SIZE_0,
+ DMA1_MASK_REG, DMA1_CLEAR_FF_REG, DMA1_MODE_REG},
+ {DMA_ADDR_1, DMA_PAGE_1, DMA_SIZE_1,
+ DMA1_MASK_REG, DMA1_CLEAR_FF_REG, DMA1_MODE_REG},
+
+ {DMA_ADDR_2, DMA_PAGE_2, DMA_SIZE_2,
+ DMA1_MASK_REG, DMA1_CLEAR_FF_REG, DMA1_MODE_REG},
+ {DMA_ADDR_3, DMA_PAGE_3, DMA_SIZE_3,
+ DMA1_MASK_REG, DMA1_CLEAR_FF_REG, DMA1_MODE_REG},
+
+ {DMA_ADDR_4, 0, DMA_SIZE_4,
+ DMA2_MASK_REG, DMA2_CLEAR_FF_REG, DMA2_MODE_REG},
+ {DMA_ADDR_5, DMA_PAGE_5, DMA_SIZE_5,
+ DMA2_MASK_REG, DMA2_CLEAR_FF_REG, DMA2_MODE_REG},
+
+ {DMA_ADDR_6, DMA_PAGE_6, DMA_SIZE_6,
+ DMA2_MASK_REG, DMA2_CLEAR_FF_REG, DMA2_MODE_REG},
+ {DMA_ADDR_7, DMA_PAGE_7, DMA_SIZE_7,
+ DMA2_MASK_REG, DMA2_CLEAR_FF_REG, DMA2_MODE_REG}
+/* *INDENT-ON* */
+};
+
+static int __initialized = 0;
+static int __buffer_count = 0;
+static __dpmi_meminfo __locked_data;
+
+int dma_initialize()
+{
+ if (!__djgpp_nearptr_enable())
+ return 0;
+
+ /* Trick: Avoid re-setting DS selector limit on each memory allocation
+ call */
+ __djgpp_selector_limit = 0xffffffff;
+
+ __locked_data.address = __djgpp_base_address + (unsigned long)&dma;
+ __locked_data.size = sizeof(dma);
+ if (__dpmi_lock_linear_region(&__locked_data))
+ return 0;
+
+ return (__initialized = 1);
+}
+
+void dma_finalize()
+{
+ if (!__initialized)
+ return;
+ __dpmi_unlock_linear_region(&__locked_data);
+ __djgpp_nearptr_disable();
+}
+
+dma_buffer *dma_allocate(unsigned int channel, unsigned int size)
+{
+ int parsize = (size + 15) >> 4; /* size in paragraphs */
+ int par = 0; /* Real-mode paragraph */
+ int selector = 0; /* Protected-mode selector */
+ int mask = channel <= 3 ? 0xfff : 0x1fff; /* Alignment mask in para. */
+ int allocsize = parsize; /* Allocated size in paragraphs */
+ int count; /* Try count */
+ int bound = 0; /* Nearest bound address */
+ int maxsize; /* Maximal possible block size */
+ dma_buffer *buffer = NULL;
+ __dpmi_meminfo buff_info, struct_info;
+
+ if (!dma_initialize())
+ return NULL;
+
+ /* Loop until we'll get a properly aligned memory block */
+ for (count = 8; count; count--) {
+ int resize = (selector != 0);
+
+ /* Try first to resize (possibly previously) allocated block */
+ if (resize) {
+ maxsize = (bound + parsize) - par;
+ if (maxsize > parsize * 2)
+ maxsize = parsize * 2;
+ if (maxsize == allocsize)
+ resize = 0;
+ else {
+ allocsize = maxsize;
+ if (__dpmi_resize_dos_memory(selector, allocsize, &maxsize) !=
+ 0) resize = 0;
+ }
+ }
+
+ if (!resize) {
+ if (selector)
+ __dpmi_free_dos_memory(selector), selector = 0;
+ par = __dpmi_allocate_dos_memory(allocsize, &selector);
+ }
+
+ if ((par == 0) || (par == -1))
+ goto exit;
+
+ /* If memory block contains a properly aligned portion, quit loop */
+ bound = (par + mask + 1) & ~mask;
+ if (par + parsize <= bound)
+ break;
+ if (bound + parsize <= par + allocsize) {
+ par = bound;
+ break;
+ }
+ }
+ if (!count) {
+ __dpmi_free_dos_memory(selector);
+ goto exit;
+ }
+
+ buffer = (dma_buffer *) MikMod_malloc(sizeof(dma_buffer));
+ buffer->linear = (unsigned char *)(__djgpp_conventional_base + bound * 16);
+ buffer->physical = bound * 16;
+ buffer->size = parsize * 16;
+ buffer->selector = selector;
+ buffer->channel = channel;
+
+ buff_info.address = buffer->physical;
+ buff_info.size = buffer->size;
+ /*
+ Don't pay attention to return code since under plain DOS it often
+ returns error (at least under HIMEM/CWSDPMI and EMM386/DPMI)
+ */
+ __dpmi_lock_linear_region(&buff_info);
+
+ /* Lock the DMA buffer control structure as well */
+ struct_info.address = __djgpp_base_address + (unsigned long)buffer;
+ struct_info.size = sizeof(dma_buffer);
+ if (__dpmi_lock_linear_region(&struct_info)) {
+ __dpmi_unlock_linear_region(&buff_info);
+ __dpmi_free_dos_memory(selector);
+ MikMod_free(buffer);
+ buffer = NULL;
+ goto exit;
+ }
+
+ exit:
+ if (buffer)
+ __buffer_count++;
+ else if (--__buffer_count == 0)
+ dma_finalize();
+ return buffer;
+}
+
+void dma_free(dma_buffer * buffer)
+{
+ __dpmi_meminfo buff_info;
+
+ if (!buffer)
+ return;
+
+ buff_info.address = buffer->physical;
+ buff_info.size = buffer->size;
+ __dpmi_unlock_linear_region(&buff_info);
+
+ __dpmi_free_dos_memory(buffer->selector);
+ MikMod_free(buffer);
+
+ if (--__buffer_count == 0)
+ dma_finalize();
+}
+
+void dma_start(dma_buffer * buffer, unsigned long count, unsigned char mode)
+{
+ /* Disable interrupts */
+ int old_ints = disable();
+ dma_disable(buffer->channel);
+ dma_set_mode(buffer->channel, mode);
+ dma_clear_ff(buffer->channel);
+ dma_set_addr(buffer->channel, buffer->physical);
+ dma_clear_ff(buffer->channel);
+ dma_set_count(buffer->channel, count);
+ dma_enable(buffer->channel);
+ /* Re-enable interrupts */
+ if (old_ints)
+ enable();
+}
+
+/* ex:set ts=4: */
projects / dosdemo / blobdiff