/* SPIM S20 MIPS simulator. Code to manipulate data segment directives. Copyright (C) 1990-1994 by James Larus (larus@cs.wisc.edu). ALL RIGHTS RESERVED. SPIM is distributed under the following conditions: You may make copies of SPIM for your own use and modify those copies. All copies of SPIM must retain my name and copyright notice. You may not sell SPIM or distributed SPIM in conjunction with a commerical product or service without the expressed written consent of James Larus. THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ /* $Header: /u/l/a/larus/Software/SPIM/src/RCS/data.c,v 3.16 1998/01/14 20:57:44 larus Exp $ */ #include "spim.h" #include "spim-utils.h" #include "inst.h" #include "mem.h" #include "reg.h" #include "sym-tbl.h" #include "parser.h" #include "run.h" #include "data.h" /* The first 64K of the data segment are dedicated to small data segment, which is pointed to by $gp. This register points to the middle of the segment, so we can use the full offset field in an instruction. */ static mem_addr next_data_pc; /* Location for next datum in user process */ static mem_addr next_k_data_pc; /* Location for next datum in kernel */ static int in_kernel = 0; /* Non-zero => data goes to kdata, not data */ #define DATA_PC (in_kernel ? next_k_data_pc : next_data_pc) #define BUMP_DATA_PC(DELTA) {if (in_kernel) \ next_k_data_pc += DELTA; \ else {next_data_pc += DELTA;}} static mem_addr next_gp_item_addr; /* Address of next item accessed off $gp */ static int auto_alignment = 1; /* Non-zero => align literal to natural bound*/ /* If TO_KERNEL is non-zero, subsequent data will be placed in the kernel data segment. If it is zero, data will go to the user's data segment.*/ #ifdef __STDC__ void user_kernel_data_segment (int to_kernel) #else void user_kernel_data_segment (to_kernel) int to_kernel; #endif { in_kernel = to_kernel; } #ifdef __STDC__ void end_of_assembly_file (void) #else void end_of_assembly_file () #endif { in_kernel = 0; auto_alignment = 1; } /* Set the point at which the first datum is stored to be ADDRESS + 64K. The 64K increment allocates an area pointed to by register $gp, which is initialized. */ #ifdef __STDC__ void data_begins_at_point (mem_addr addr) #else void data_begins_at_point (addr) mem_addr addr; #endif { if (bare_machine) next_data_pc = addr; else { next_gp_item_addr = addr; gp_midpoint = addr + 32*K; R[REG_GP] = gp_midpoint; next_data_pc = addr + 64 * K; } } /* Set the point at which the first datum is stored in the kernel's data segment. */ #ifdef __STDC__ void k_data_begins_at_point (mem_addr addr) #else void k_data_begins_at_point (addr) mem_addr addr; #endif { next_k_data_pc = addr; } /* Arrange that the next datum is stored on a memory boundary with its low ALIGNMENT bits equal to 0. If argument is 0, disable automatic alignment.*/ #ifdef __STDC__ void align_data (int alignment) #else void align_data (alignment) int alignment; #endif { if (alignment == 0) auto_alignment = 0; else if (in_kernel) { next_k_data_pc = (next_k_data_pc + (1 << alignment) - 1) & (-1 << alignment); fix_current_label_address (next_k_data_pc); } else { next_data_pc = (next_data_pc + (1 << alignment) - 1) & (-1 << alignment); fix_current_label_address (next_data_pc); } } #ifdef __STDC__ void set_data_alignment (int alignment) #else void set_data_alignment (alignment) int alignment; #endif { if (auto_alignment) align_data (alignment); } #ifdef __STDC__ void enable_data_alignment (void) #else void enable_data_alignment () #endif { auto_alignment = 1; } /* Set the location (in user or kernel data space) for the next datum. */ #ifdef __STDC__ void set_data_pc (mem_addr addr) #else void set_data_pc (addr) mem_addr addr; #endif { if (in_kernel) next_k_data_pc = addr; else next_data_pc = addr; } /* Return the address at which the next datum will be stored. */ #ifdef __STDC__ mem_addr current_data_pc (void) #else mem_addr current_data_pc () #endif { return (DATA_PC); } /* Bump the address at which the next data will be stored by VALUE bytes. */ #ifdef __STDC__ void increment_data_pc (int value) #else void increment_data_pc (value) int value; #endif { BUMP_DATA_PC (value); } /* Process a .extern NAME SIZE directive. */ #ifdef __STDC__ void extern_directive (char *name, int size) #else void extern_directive (name, size) char *name; int size; #endif { label *sym = make_label_global (name); if (!bare_machine && size > 0 && size <= SMALL_DATA_SEG_MAX_SIZE && next_gp_item_addr + size < gp_midpoint + 32*K) { sym->gp_flag = 1; sym->addr = next_gp_item_addr; next_gp_item_addr += size; } } /* Process a .lcomm NAME SIZE directive. */ #ifdef __STDC__ void lcomm_directive (char *name, int size) #else void lcomm_directive (name, size) char *name; int size; #endif { label *sym = lookup_label (name); if (!bare_machine && size > 0 && size <= SMALL_DATA_SEG_MAX_SIZE && next_gp_item_addr + size < gp_midpoint + 32*K) { sym->gp_flag = 1; sym->addr = next_gp_item_addr; next_gp_item_addr += size; } /* Don't need to initialize since memory starts with 0's */ } /* Process a .ascii STRING or .asciiz STRING directive. */ #ifdef __STDC__ void store_string (char *string, int length, int null_terminate) #else void store_string (string, length, null_terminate) char *string; int length; int null_terminate; #endif { for ( ; length > 0; string ++, length --) { SET_MEM_BYTE (DATA_PC, *string); BUMP_DATA_PC(1); } if (null_terminate) { SET_MEM_BYTE (DATA_PC, 0); BUMP_DATA_PC(1); } } /* Process a .byte EXPR directive. */ #ifdef __STDC__ void store_byte (int value) #else void store_byte (value) int value; #endif { SET_MEM_BYTE (DATA_PC, value); BUMP_DATA_PC (1); } /* Process a .half EXPR directive. */ #ifdef __STDC__ void store_half (int value) #else void store_half (value) int value; #endif { if (DATA_PC & 0x1) { #ifdef BIGENDIAN store_byte ((value >> 8) & 0xff); store_byte (value & 0xff); #else store_byte (value & 0xff); store_byte ((value >> 8) & 0xff); #endif } else { SET_MEM_HALF (DATA_PC, value); BUMP_DATA_PC (BYTES_PER_WORD / 2); } } /* Process a .word EXPR directive. */ #ifdef __STDC__ void store_word (int value) #else void store_word (value) int value; #endif { if (DATA_PC & 0x3) { #ifdef BIGENDIAN store_half ((value >> 16) & 0xffff); store_half (value & 0xffff); #else store_half (value & 0xffff); store_half ((value >> 16) & 0xffff); #endif } else { SET_MEM_WORD (DATA_PC, value); BUMP_DATA_PC (BYTES_PER_WORD); } } /* Process a .double EXPR directive. */ #ifdef __STDC__ void store_double (double *value) #else void store_double (value) double *value; #endif { if (DATA_PC & 0x7) { store_word (* ((mem_word *) value)); store_word (* (((mem_word *) value) + 1)); } else { SET_MEM_WORD (DATA_PC, * ((mem_word *) value)); BUMP_DATA_PC (BYTES_PER_WORD); SET_MEM_WORD (DATA_PC, * (((mem_word *) value) + 1)); BUMP_DATA_PC (BYTES_PER_WORD); } } /* Process a .float EXPR directive. */ #ifdef __STDC__ void store_float (double *value) #else void store_float (value) double *value; #endif { float val = (float)*value; float *vp = &val; if (DATA_PC & 0x3) { store_half (*(mem_word *) vp & 0xffff); store_half ((*(mem_word *) vp >> 16) & 0xffff); } else { SET_MEM_WORD (DATA_PC, *((mem_word *) vp)); BUMP_DATA_PC (BYTES_PER_WORD); } }