54 lines
1.1 KiB
C
54 lines
1.1 KiB
C
/* $Source$
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* $State$
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* $Revision$
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*/
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#include <stdlib.h>
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#include <errno.h>
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#include <unistd.h>
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#include <cpm.h>
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ssize_t read(int fd, void* buffer, size_t count)
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{
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short save;
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unsigned char before_n;
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/* We're only allowed to read from fd 0, 1 or 2. */
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if ((fd < 0) || (fd > 2))
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{
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errno = EBADF;
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return -1;
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}
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/* We need room for at least 1 char plus '\n'. */
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if (count < 2)
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{
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errno = EINVAL;
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return -1;
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}
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/* Make room to append '\n' later. */
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before_n = count > 255 ? 255 : count - 1;
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/* Borrow 2 bytes of RAM before the buffer. */
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/* This might overwrite count!!! */
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save = ((short*)buffer)[-1];
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/* Read one line from the console. */
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((unsigned char*)buffer)[-2] = before_n;
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cpm_bc_register = CPM_BDOS_READ_CONSOLE_BUFFER;
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cpm_de_register = (uint16_t)(char*)buffer - 2;
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cpm_bdos();
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before_n = ((unsigned char*)buffer)[-1];
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((char*)buffer)[before_n] = '\n'; /* Append '\n'. */
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((short*)buffer)[-1] = save; /* Give back borrowed bytes. */
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/* Echo '\n' to console. */
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cpm_bc_register = CPM_BDOS_PRINT_STRING;
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cpm_de_register = (uint16_t)"\r\n$";
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cpm_bdos();
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return (int)before_n + 1;
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}
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