【龙芯1c库】移植硬浮点FPU
龙芯1c库是把龙芯1c的常用外设的常用功能封装为一个库，类似于STM32库。完整源码请移步到https://gitee.com/caogos/OpenLoongsonLib1c
龙芯1C上有硬浮点协处理器，整个移植过程主要参考《see mips run 中文版.pdf》中第7章“浮点支持”。文档《see mips run 中文版.pdf》可以在“https://gitee.com/caogos/OpenLoongsonLib1c/tree/master/doc”里面下载。
硬浮点FPU的使用没什么说的，就是在程序中需要使用浮点数时正常使用就行，本文重点放在移植上。
按图索骥
看看《see mips run 中文版.pdf》中怎么说的
文档《see mips run 中文版.pdf》的第7章用了一节的内容来详细讲解CPU复位后，应该怎样初始化FPU。如下图
文中已经描述得很清楚了。
第一步：使能协处理器1——FPU
第二步：设置控制/状态寄存器FCSR中的舍入模式和自陷使能
如果是裸机编程，执行以上两步就足够了；如果是移植到实时系统（比如RT-Thread）下，还需要执行
第三步：在中断和上下文切换时保存和恢复浮点寄存器。
浮点异常（自陷）
通常禁止全部浮点自陷
再来仔细看下上面那段话
这段话明确讲了通常是怎样设置舍入模式和自陷使能的。通常会禁止全部自陷，还要设置SR（FS）位让很小的结果返回零，这样可以免去一个到仿真程序的自陷。
浮点异常产生的原因
文中说“当一个浮点操作不能产生正确的结果时，就会发生一个MIPS异常”。那在哪些情况下不能产生正确的结果呢？
上图为FPU的控制/状态寄存器中关于异常的几个位的解释。共五种可能产生异常的原因——无效操作、除以零、上溢、下溢和非精确。在FPU的控制/状态寄存器中的位置如下
如果使能了FPU异常，并且也发生了异常，那么会触发cpu的异常，具体为协处理器0的cause寄存器中的FPE位被置位。根据前面的介绍，一般情况是禁止全部浮点异常，所以可以不用考虑触发cpu的异常。
FPU寄存器简介
浮点控制状态寄存器
寄存器简介
控制/状态寄存器很重要，配置FPU就是配置这个寄存器。包括舍入模式和禁止全部中断都是操作这个寄存器。
另外还需要注意的一个地方是，操作控制/状态寄存器的汇编指令为ctc1和cfc1。其中cfc1用来读取寄存器的值，ctc1将值写入寄存器。
寄存器的读写
代码中将cfc1和ctc1封装为宏，并且进一步为控制/状态寄存器的读和写分别封装了一个宏，便于编程时直接调用。具体代码如下
/*
* Macros to access the floating point coprocessor control registers
*/
#define read_32bit_cp1_register(source) \
({ int __res; \
__asm__ __volatile__( \
".set\tpush\n\t" \
".set\treorder\n\t" \
/* gas fails to assemble cfc1 for some archs (octeon).*/ \
".set\tmips1\n\t" \
"cfc1\t%0,"STR(source)"\n\t" \
".set\tpop" \
: "=r" (__res)); \
__res;})
#define write_32bit_cp1_register(register, value) \
do { \
__asm__ __volatile__( \
"ctc1\t%z0, "STR(register)"\n\t" \
: : "Jr" ((unsigned int)(value))); \
} while (0)
#define read_c1_status() read_32bit_cp1_register(CP1_STATUS)
#define read_c1_revision() read_32bit_cp1_register(CP1_REVISION);
#define write_c1_status(val) write_32bit_cp1_register(CP1_STATUS, val)
宏read_32bit_cp1_register(source)用于读取寄存器的值，宏write_32bit_cp1_register(register, value)向寄存器写入数据。
read_c1_status()读取控制/状态寄存器的值，read_c1_revision()读取浮点实现寄存器的值（浮点实现寄存器在后面介绍），write_c1_status(val)修改控制/状态寄存器。
其中，CP1_STATUS和CP1_REVISION为寄存器编号，如下
/*
* Coprocessor 1 (FPU) register names
*/
#define CP1_REVISION $0
#define CP1_STATUS $31
寄存器的配置
根据上一章的分析，裸机编程时，FPU的初始化只需要两步。一：使能FPU，二：配置FPU的控制/状态寄存器（舍入模式、禁止全部中断）。用代码表示为
// 硬浮点初始化
void fpu_init(void)
{
unsigned int c0_status = 0;
unsigned int c1_status = 0;
// 使能协处理器1--FPU
c0_status = read_c0_status();
c0_status |= (ST0_CU1 | ST0_FR);
write_c0_status(c0_status);
// 配置FPU
c1_status = read_c1_status();
c1_status |= (FPU_CSR_FS | FPU_CSR_FO | FPU_CSR_FN); // set FS, FO, FN
c1_status &= ~(FPU_CSR_ALL_E); // disable exception
c1_status = (c1_status & (~FPU_CSR_RM)) | FPU_CSR_RN; // set RN
write_c1_status(c1_status);
return ;
}
裸机编程中只需要在初始化的时候调用fpu_init()，就可以在裸机编程中使用硬浮点FPU了，
其中，FPU_CSR_FS、FPU_CSR_FO、FPU_CSR_FN、FPU_CSR_ALL_E、FPU_CSR_RM、FPU_CSR_RN为FPU的控制/状态寄存器的某个位域，用宏表示为
/*
* FPU Status Register Values
*/
/*
* Status Register Values
*/
#define FPU_CSR_FLUSH 0x01000000 /* flush denormalised results to 0 */
#define FPU_CSR_COND 0x00800000 /* $fcc0 */
#define FPU_CSR_COND0 0x00800000 /* $fcc0 */
#define FPU_CSR_COND1 0x02000000 /* $fcc1 */
#define FPU_CSR_COND2 0x04000000 /* $fcc2 */
#define FPU_CSR_COND3 0x08000000 /* $fcc3 */
#define FPU_CSR_COND4 0x10000000 /* $fcc4 */
#define FPU_CSR_COND5 0x20000000 /* $fcc5 */
#define FPU_CSR_COND6 0x40000000 /* $fcc6 */
#define FPU_CSR_COND7 0x80000000 /* $fcc7 */
/* FS/FO/FN */
#define FPU_CSR_FS 0x01000000
#define FPU_CSR_FO 0x00400000
#define FPU_CSR_FN 0x00200000
/*
* Bits 18 - 20 of the FPU Status Register will be read as 0,
* and should be written as zero.
*/
#define FPU_CSR_RSVD 0x001c0000
/*
* X the exception cause indicator
* E the exception enable
* S the sticky/flag bit
*/
#define FPU_CSR_ALL_X 0x0003f000
#define FPU_CSR_UNI_X 0x00020000
#define FPU_CSR_INV_X 0x00010000
#define FPU_CSR_DIV_X 0x00008000
#define FPU_CSR_OVF_X 0x00004000
#define FPU_CSR_UDF_X 0x00002000
#define FPU_CSR_INE_X 0x00001000
#define FPU_CSR_ALL_E 0x00000f80
#define FPU_CSR_INV_E 0x00000800
#define FPU_CSR_DIV_E 0x00000400
#define FPU_CSR_OVF_E 0x00000200
#define FPU_CSR_UDF_E 0x00000100
#define FPU_CSR_INE_E 0x00000080
#define FPU_CSR_ALL_S 0x0000007c
#define FPU_CSR_INV_S 0x00000040
#define FPU_CSR_DIV_S 0x00000020
#define FPU_CSR_OVF_S 0x00000010
#define FPU_CSR_UDF_S 0x00000008
#define FPU_CSR_INE_S 0x00000004
/* Bits 0 and 1 of FPU Status Register specify the rounding mode */
#define FPU_CSR_RM 0x00000003
#define FPU_CSR_RN 0x0 /* nearest */
#define FPU_CSR_RZ 0x1 /* towards zero */
#define FPU_CSR_RU 0x2 /* towards +Infinity */
#define FPU_CSR_RD 0x3 /* towards -Infinity */
浮点实现寄存器
老规矩，先来看看《see mips run》怎么说的。
重点注意F64、L、W、D、S这几个位的值。
浮点实现寄存器的存取也是使用cfc1和ctc1，上一节已经给出了封装好的宏——read_c1_revision()
龙芯1c的芯片手册中说了龙芯1C有FPU，所以是否查看这个寄存器其实不太重要。但是如果要移植到实时系统（比如RT-Thread），就必须查看此寄存器的值了。特别是位域F64，这个位域告诉我们龙芯1C上的FPU是不是老式的MIPS I风格的浮点单元。
既然这样，那就在RT-Thread下把这个寄存器的值读取出来看看，如下
源码为
rt_uint32_t c1_revision = 0;
c1_revision = read_c1_revision();
rt_kprintf("[%s] c1 FIR=0x%x\n", __FUNCTION__, c1_revision);
从上图可知，F64=0，即龙芯1C上的FPU为老式的MIPS I风格。不要看见这是，认为龙芯1C使用的是老式的MIPS I风格的FPU，感觉不爽，实际上很多嵌入式上的FPU都是使用的MIPS I风格的老式FPU，这对嵌入式应用来说足够了。
浮点运算需要用到的寄存器
寄存器简介
注意，这里的浮点寄存器是用于浮点运算的寄存器，不是前面提到的控制/状态寄存器和实现寄存器。这里的寄存器类似于CPU上的32个通用寄存器（t0,t1,v1,v2,a0,a1,sp,gp,k0,k1等）。
综上所述：龙芯1C使用的是老式的MIPS I风格的FPU，即ABI为o32。只有16个偶数号的寄存器可以用于计算，在实时系统RT-Thread的中断和上下文切换时需要保存的也就是这16个寄存器。
寄存器的读写
前面提到——FPU的控制/状态寄存器和实现寄存器使用cfc1和ctc1来存取寄存器，其中FPU控制/状态寄存器FCSR的编号为31，用$31表示；FPU实现寄存器FIR的编号为0，用$0表示。
本小节讨论的用于浮点运算的寄存器也有32个，只是龙芯1C的FPU为老式的MIPS I风格的，只使用编号为偶数的16个寄存器。分别用$f0, $f2, $f4, ...... , $f28, $f30。
注意，用于计算的32个寄存器编号中多了一个f。
与整数的运算类似，浮点运算也有加减乘除，为此还专门为FPU创建了一套指令，如下
移植FPU时，只需要在中断和上下文切换时保存用于浮点计算的16个寄存器就行，所以这里只关注Load/Store指令。
总结一下龙芯1C上FPU的Load/Store指令的要点：
1，只有16个偶数编号的寄存器参与浮点运算
2，优先使用合成指令，比如l.d $f0, 0(sp)
3，统一八字节对齐
尤其，特别注意字节对齐的问题。在中断和上下文切换时，先要将sp指针8字节对齐，然后再压栈或出栈。合成指令l.d $f0, 0(sp)实际上是将$f0和$f1两个寄存器中的值压栈了。
建议所有的栈都八字节对齐，包括实时系统中每个任务的栈。
中断处理程序中是不推荐有浮点运算的，其它比较耗时的也不允许，比如printf（）打印函数等。正因为这个原因，所以裸机编程时没必要在中断中保存FPU寄存器，特殊情况除外。
源码清单
这里只展示裸机编程时涉及FPU的源码，更多的源码请移步到文章开头给出的git 地址里面查看，关于把FPU移植到RT-Thread会另外单独写一篇文章。
main.c
#include "../lib/ls1c_public.h"
#include "../lib/ls1c_gpio.h"
#include "../lib/ls1c_delay.h"
#include "../lib/ls1c_mipsregs.h"
#include "../example/test_gpio.h"
#include "../example/test_pwm.h"
#include "../example/test_delay.h"
#include "../example/test_simulate_i2c.h"
#include "../example/test_timer.h"
#include "../example/test_fpu.h"
// pmon提供的打印接口
struct callvectors *callvec;
// 硬浮点初始化
void fpu_init(void)
{
unsigned int c0_status = 0;
unsigned int c1_status = 0;
// 使能协处理器1--FPU
c0_status = read_c0_status();
c0_status |= (ST0_CU1 | ST0_FR);
write_c0_status(c0_status);
// 配置FPU
c1_status = read_c1_status();
c1_status |= (FPU_CSR_FS | FPU_CSR_FO | FPU_CSR_FN); // set FS, FO, FN
c1_status &= ~(FPU_CSR_ALL_E); // disable exception
c1_status = (c1_status & (~FPU_CSR_RM)) | FPU_CSR_RN; // set RN
write_c1_status(c1_status);
return ;
}
void bsp_init(void)
{
// 硬浮点初始化
fpu_init();
return ;
}
int main(int argc, char **argv, char **env, struct callvectors *cv)
{
callvec = cv; // 这条语句之后才能使用pmon提供的打印功能
bsp_init();
// -------------------------测试gpio----------------------
/*
* 测试库中gpio作为输出时的相关接口
* led闪烁10次
*/
// test_gpio_output();
/*
* 测试库中gpio作为输入时的相关接口
* 按键按下时，指示灯点亮，否则，熄灭
*/
// test_gpio_input();
// ------------------------测试PWM--------------------------------
// 测试硬件pwm产生连续的pwm波形
// test_pwm_normal();
// 测试硬件pwm产生pwm脉冲
// test_pwm_pulse();
/*
* 测试gpio04复用为pwm,gpio06作为普通gpio使用
* PWM0的默认引脚位GPIO06，但也可以复用为GPIO04
* 当gpio06还是保持默认为pwm时，复用gpio04为pwm0，那么会同时在两个引脚输出相同的pwm波形
* 本函数旨在证明可以在gpio04复用为pwm0时，还可以将(默认作为pwm0的)gpio06作为普通gpio使用
*/
// test_pwm_gpio04_gpio06();
// 测试pwm最大周期
// test_pwm_max_period();
// ------------------------测试软件延时--------------------------------
// 测试延时函数delay_1ms()
// test_delay_1ms();
// 测试延时函数delay_1us()
// test_delay_1us();
// 测试延时函数delay_1s()
// test_delay_1s();
// ------------------------测试模拟I2C------------------------------
// 测试模拟I2C
// test_simulate_i2c_am2320();
// ------------------------测试硬件定时器---------------------------
// 测试硬件定时器的定时功能(读取中断状态位的方式判断是否超时)
// test_timer_poll_time_out();
// 测试硬件定时器的计时
// test_timer_get_time();
// ------------------------测试硬浮点(FPU)---------------------------
// 测试使用硬浮点进行浮点数的加减乘除
test_fpu();
return(0);
}
ls1c_mipsregs.h
/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1994, 1995, 1996, 1997, 2000, 2001 by Ralf Baechle
* Copyright (C) 2000 Silicon Graphics, Inc.
* Modified for further R[236]000 support by Paul M. Antoine, 1996.
* Kevin D. Kissell, [email protected] and Carsten Langgaard, [email protected]
* Copyright (C) 2000, 07 MIPS Technologies, Inc.
* Copyright (C) 2003, 2004 Maciej W. Rozycki
*
* Change Logs:
* Date Author Notes
*
*/
#ifndef __MIPSREGS_H__
#define __MIPSREGS_H__
/*
* The following macros are especially useful for __asm__
* inline assembler.
*/
#ifndef __STR
#define __STR(x) #x
#endif
#ifndef STR
#define STR(x) __STR(x)
#endif
/*
* Configure language
*/
#ifdef __ASSEMBLY__
#define _ULCAST_
#else
#define _ULCAST_ (unsigned long)
#endif
/*
* Coprocessor 0 register names
*/
#define CP0_INDEX $0
#define CP0_RANDOM $1
#define CP0_ENTRYLO0 $2
#define CP0_ENTRYLO1 $3
#define CP0_CONF $3
#define CP0_CONTEXT $4
#define CP0_PAGEMASK $5
#define CP0_WIRED $6
#define CP0_INFO $7
#define CP0_BADVADDR $8
#define CP0_COUNT $9
#define CP0_ENTRYHI $10
#define CP0_COMPARE $11
#define CP0_STATUS $12
#define CP0_CAUSE $13
#define CP0_EPC $14
#define CP0_PRID $15
#define CP0_CONFIG $16
#define CP0_LLADDR $17
#define CP0_WATCHLO $18
#define CP0_WATCHHI $19
#define CP0_XCONTEXT $20
#define CP0_FRAMEMASK $21
#define CP0_DIAGNOSTIC $22
#define CP0_DEBUG $23
#define CP0_DEPC $24
#define CP0_PERFORMANCE $25
#define CP0_ECC $26
#define CP0_CACHEERR $27
#define CP0_TAGLO $28
#define CP0_TAGHI $29
#define CP0_ERROREPC $30
#define CP0_DESAVE $31
/*
* R4640/R4650 cp0 register names. These registers are listed
* here only for completeness; without MMU these CPUs are not useable
* by Linux. A future ELKS port might take make Linux run on them
* though ...
*/
#define CP0_IBASE $0
#define CP0_IBOUND $1
#define CP0_DBASE $2
#define CP0_DBOUND $3
#define CP0_CALG $17
#define CP0_IWATCH $18
#define CP0_DWATCH $19
/*
* Coprocessor 0 Set 1 register names
*/
#define CP0_S1_DERRADDR0 $26
#define CP0_S1_DERRADDR1 $27
#define CP0_S1_INTCONTROL $20
/*
* Coprocessor 0 Set 2 register names
*/
#define CP0_S2_SRSCTL $12 /* MIPSR2 */
/*
* Coprocessor 0 Set 3 register names
*/
#define CP0_S3_SRSMAP $12 /* MIPSR2 */
/*
* TX39 Series
*/
#define CP0_TX39_CACHE $7
/*
* Coprocessor 1 (FPU) register names
*/
#define CP1_REVISION $0
#define CP1_STATUS $31
/*
* FPU Status Register Values
*/
/*
* Status Register Values
*/
#define FPU_CSR_FLUSH 0x01000000 /* flush denormalised results to 0 */
#define FPU_CSR_COND 0x00800000 /* $fcc0 */
#define FPU_CSR_COND0 0x00800000 /* $fcc0 */
#define FPU_CSR_COND1 0x02000000 /* $fcc1 */
#define FPU_CSR_COND2 0x04000000 /* $fcc2 */
#define FPU_CSR_COND3 0x08000000 /* $fcc3 */
#define FPU_CSR_COND4 0x10000000 /* $fcc4 */
#define FPU_CSR_COND5 0x20000000 /* $fcc5 */
#define FPU_CSR_COND6 0x40000000 /* $fcc6 */
#define FPU_CSR_COND7 0x80000000 /* $fcc7 */
/* FS/FO/FN */
#define FPU_CSR_FS 0x01000000
#define FPU_CSR_FO 0x00400000
#define FPU_CSR_FN 0x00200000
/*
* Bits 18 - 20 of the FPU Status Register will be read as 0,
* and should be written as zero.
*/
#define FPU_CSR_RSVD 0x001c0000
/*
* X the exception cause indicator
* E the exception enable
* S the sticky/flag bit
*/
#define FPU_CSR_ALL_X 0x0003f000
#define FPU_CSR_UNI_X 0x00020000
#define FPU_CSR_INV_X 0x00010000
#define FPU_CSR_DIV_X 0x00008000
#define FPU_CSR_OVF_X 0x00004000
#define FPU_CSR_UDF_X 0x00002000
#define FPU_CSR_INE_X 0x00001000
#define FPU_CSR_ALL_E 0x00000f80
#define FPU_CSR_INV_E 0x00000800
#define FPU_CSR_DIV_E 0x00000400
#define FPU_CSR_OVF_E 0x00000200
#define FPU_CSR_UDF_E 0x00000100
#define FPU_CSR_INE_E 0x00000080
#define FPU_CSR_ALL_S 0x0000007c
#define FPU_CSR_INV_S 0x00000040
#define FPU_CSR_DIV_S 0x00000020
#define FPU_CSR_OVF_S 0x00000010
#define FPU_CSR_UDF_S 0x00000008
#define FPU_CSR_INE_S 0x00000004
/* Bits 0 and 1 of FPU Status Register specify the rounding mode */
#define FPU_CSR_RM 0x00000003
#define FPU_CSR_RN 0x0 /* nearest */
#define FPU_CSR_RZ 0x1 /* towards zero */
#define FPU_CSR_RU 0x2 /* towards +Infinity */
#define FPU_CSR_RD 0x3 /* towards -Infinity */
/*
* R4x00 interrupt enable / cause bits
*/
#define IE_SW0 (_ULCAST_(1) << 8)
#define IE_SW1 (_ULCAST_(1) << 9)
#define IE_IRQ0 (_ULCAST_(1) << 10)
#define IE_IRQ1 (_ULCAST_(1) << 11)
#define IE_IRQ2 (_ULCAST_(1) << 12)
#define IE_IRQ3 (_ULCAST_(1) << 13)
#define IE_IRQ4 (_ULCAST_(1) << 14)
#define IE_IRQ5 (_ULCAST_(1) << 15)
/*
* R4x00 interrupt cause bits
*/
#define C_SW0 (_ULCAST_(1) << 8)
#define C_SW1 (_ULCAST_(1) << 9)
#define C_IRQ0 (_ULCAST_(1) << 10)
#define C_IRQ1 (_ULCAST_(1) << 11)
#define C_IRQ2 (_ULCAST_(1) << 12)
#define C_IRQ3 (_ULCAST_(1) << 13)
#define C_IRQ4 (_ULCAST_(1) << 14)
#define C_IRQ5 (_ULCAST_(1) << 15)
/*
* Bitfields in the R4xx0 cp0 status register
*/
#define ST0_IE 0x00000001
#define ST0_EXL 0x00000002
#define ST0_ERL 0x00000004
#define ST0_KSU 0x00000018
# define KSU_USER 0x00000010
# define KSU_SUPERVISOR 0x00000008
# define KSU_KERNEL 0x00000000
#define ST0_UX 0x00000020
#define ST0_SX 0x00000040
#define ST0_KX 0x00000080
#define ST0_DE 0x00010000
#define ST0_CE 0x00020000
/*
* Setting c0_status.co enables Hit_Writeback and Hit_Writeback_Invalidate
* cacheops in userspace. This bit exists only on RM7000 and RM9000
* processors.
*/
#define ST0_CO 0x08000000
/*
* Bitfields in the R[23]000 cp0 status register.
*/
#define ST0_IEC 0x00000001
#define ST0_KUC 0x00000002
#define ST0_IEP 0x00000004
#define ST0_KUP 0x00000008
#define ST0_IEO 0x00000010
#define ST0_KUO 0x00000020
/* bits 6 & 7 are reserved on R[23]000 */
#define ST0_ISC 0x00010000
#define ST0_SWC 0x00020000
#define ST0_CM 0x00080000
/*
* Bits specific to the R4640/R4650
*/
#define ST0_UM (_ULCAST_(1) << 4)
#define ST0_IL (_ULCAST_(1) << 23)
#define ST0_DL (_ULCAST_(1) << 24)
/*
* Enable the MIPS DSP ASE
*/
#define ST0_MX 0x01000000
/*
* Bitfields in the TX39 family CP0 Configuration Register 3
*/
#define TX39_CONF_ICS_SHIFT 19
#define TX39_CONF_ICS_MASK 0x00380000
#define TX39_CONF_ICS_1KB 0x00000000
#define TX39_CONF_ICS_2KB 0x00080000
#define TX39_CONF_ICS_4KB 0x00100000
#define TX39_CONF_ICS_8KB 0x00180000
#define TX39_CONF_ICS_16KB 0x00200000
#define TX39_CONF_DCS_SHIFT 16
#define TX39_CONF_DCS_MASK 0x00070000
#define TX39_CONF_DCS_1KB 0x00000000
#define TX39_CONF_DCS_2KB 0x00010000
#define TX39_CONF_DCS_4KB 0x00020000
#define TX39_CONF_DCS_8KB 0x00030000
#define TX39_CONF_DCS_16KB 0x00040000
#define TX39_CONF_CWFON 0x00004000
#define TX39_CONF_WBON 0x00002000
#define TX39_CONF_RF_SHIFT 10
#define TX39_CONF_RF_MASK 0x00000c00
#define TX39_CONF_DOZE 0x00000200
#define TX39_CONF_HALT 0x00000100
#define TX39_CONF_LOCK 0x00000080
#define TX39_CONF_ICE 0x00000020
#define TX39_CONF_DCE 0x00000010
#define TX39_CONF_IRSIZE_SHIFT 2
#define TX39_CONF_IRSIZE_MASK 0x0000000c
#define TX39_CONF_DRSIZE_SHIFT 0
#define TX39_CONF_DRSIZE_MASK 0x00000003
/*
* Status register bits available in all MIPS CPUs.
*/
#define ST0_IM 0x0000ff00
#define STATUSB_IP0 8
#define STATUSF_IP0 (_ULCAST_(1) << 8)
#define STATUSB_IP1 9
#define STATUSF_IP1 (_ULCAST_(1) << 9)
#define STATUSB_IP2 10
#define STATUSF_IP2 (_ULCAST_(1) << 10)
#define STATUSB_IP3 11
#define STATUSF_IP3 (_ULCAST_(1) << 11)
#define STATUSB_IP4 12
#define STATUSF_IP4 (_ULCAST_(1) << 12)
#define STATUSB_IP5 13
#define STATUSF_IP5 (_ULCAST_(1) << 13)
#define STATUSB_IP6 14
#define STATUSF_IP6 (_ULCAST_(1) << 14)
#define STATUSB_IP7 15
#define STATUSF_IP7 (_ULCAST_(1) << 15)
#define STATUSB_IP8 0
#define STATUSF_IP8 (_ULCAST_(1) << 0)
#define STATUSB_IP9 1
#define STATUSF_IP9 (_ULCAST_(1) << 1)
#define STATUSB_IP10 2
#define STATUSF_IP10 (_ULCAST_(1) << 2)
#define STATUSB_IP11 3
#define STATUSF_IP11 (_ULCAST_(1) << 3)
#define STATUSB_IP12 4
#define STATUSF_IP12 (_ULCAST_(1) << 4)
#define STATUSB_IP13 5
#define STATUSF_IP13 (_ULCAST_(1) << 5)
#define STATUSB_IP14 6
#define STATUSF_IP14 (_ULCAST_(1) << 6)
#define STATUSB_IP15 7
#define STATUSF_IP15 (_ULCAST_(1) << 7)
#define ST0_CH 0x00040000
#define ST0_SR 0x00100000
#define ST0_TS 0x00200000
#define ST0_BEV 0x00400000
#define ST0_RE 0x02000000
#define ST0_FR 0x04000000
#define ST0_CU 0xf0000000
#define ST0_CU0 0x10000000
#define ST0_CU1 0x20000000
#define ST0_CU2 0x40000000
#define ST0_CU3 0x80000000
#define ST0_XX 0x80000000 /* MIPS IV naming */
/*
* Bitfields and bit numbers in the coprocessor 0 cause register.
*
* Refer to your MIPS R4xx0 manual, chapter 5 for explanation.
*/
#define CAUSEB_EXCCODE 2
#define CAUSEF_EXCCODE (_ULCAST_(31) << 2)
#define CAUSEB_IP 8
#define CAUSEF_IP (_ULCAST_(255) << 8)
#define CAUSEB_IP0 8
#define CAUSEF_IP0 (_ULCAST_(1) << 8)
#define CAUSEB_IP1 9
#define CAUSEF_IP1 (_ULCAST_(1) << 9)
#define CAUSEB_IP2 10
#define CAUSEF_IP2 (_ULCAST_(1) << 10)
#define CAUSEB_IP3 11
#define CAUSEF_IP3 (_ULCAST_(1) << 11)
#define CAUSEB_IP4 12
#define CAUSEF_IP4 (_ULCAST_(1) << 12)
#define CAUSEB_IP5 13
#define CAUSEF_IP5 (_ULCAST_(1) << 13)
#define CAUSEB_IP6 14
#define CAUSEF_IP6 (_ULCAST_(1) << 14)
#define CAUSEB_IP7 15
#define CAUSEF_IP7 (_ULCAST_(1) << 15)
#define CAUSEB_IV 23
#define CAUSEF_IV (_ULCAST_(1) << 23)
#define CAUSEB_CE 28
#define CAUSEF_CE (_ULCAST_(3) << 28)
#define CAUSEB_BD 31
#define CAUSEF_BD (_ULCAST_(1) << 31)
/*
* Bits in the coprocessor 0 config register.
*/
/* Generic bits. */
#define CONF_CM_CACHABLE_NO_WA 0
#define CONF_CM_CACHABLE_WA 1
#define CONF_CM_UNCACHED 2
#define CONF_CM_CACHABLE_NONCOHERENT 3
#define CONF_CM_CACHABLE_CE 4
#define CONF_CM_CACHABLE_COW 5
#define CONF_CM_CACHABLE_CUW 6
#define CONF_CM_CACHABLE_ACCELERATED 7
#define CONF_CM_CMASK 7
#define CONF_BE (_ULCAST_(1) << 15)
/* Bits common to various processors. */
#define CONF_CU (_ULCAST_(1) << 3)
#define CONF_DB (_ULCAST_(1) << 4)
#define CONF_IB (_ULCAST_(1) << 5)
#define CONF_DC (_ULCAST_(7) << 6)
#define CONF_IC (_ULCAST_(7) << 9)
#define CONF_EB (_ULCAST_(1) << 13)
#define CONF_EM (_ULCAST_(1) << 14)
#define CONF_SM (_ULCAST_(1) << 16)
#define CONF_SC (_ULCAST_(1) << 17)
#define CONF_EW (_ULCAST_(3) << 18)
#define CONF_EP (_ULCAST_(15)<< 24)
#define CONF_EC (_ULCAST_(7) << 28)
#define CONF_CM (_ULCAST_(1) << 31)
/* Bits specific to the R4xx0. */
#define R4K_CONF_SW (_ULCAST_(1) << 20)
#define R4K_CONF_SS (_ULCAST_(1) << 21)
#define R4K_CONF_SB (_ULCAST_(3) << 22)
/* Bits specific to the R5000. */
#define R5K_CONF_SE (_ULCAST_(1) << 12)
#define R5K_CONF_SS (_ULCAST_(3) << 20)
/* Bits specific to the RM7000. */
#define RM7K_CONF_SE (_ULCAST_(1) << 3)
#define RM7K_CONF_TE (_ULCAST_(1) << 12)
#define RM7K_CONF_CLK (_ULCAST_(1) << 16)
#define RM7K_CONF_TC (_ULCAST_(1) << 17)
#define RM7K_CONF_SI (_ULCAST_(3) << 20)
#define RM7K_CONF_SC (_ULCAST_(1) << 31)
/* Bits specific to the R10000. */
#define R10K_CONF_DN (_ULCAST_(3) << 3)
#define R10K_CONF_CT (_ULCAST_(1) << 5)
#define R10K_CONF_PE (_ULCAST_(1) << 6)
#define R10K_CONF_PM (_ULCAST_(3) << 7)
#define R10K_CONF_EC (_ULCAST_(15)<< 9)
#define R10K_CONF_SB (_ULCAST_(1) << 13)
#define R10K_CONF_SK (_ULCAST_(1) << 14)
#define R10K_CONF_SS (_ULCAST_(7) << 16)
#define R10K_CONF_SC (_ULCAST_(7) << 19)
#define R10K_CONF_DC (_ULCAST_(7) << 26)
#define R10K_CONF_IC (_ULCAST_(7) << 29)
/* Bits specific to the VR41xx. */
#define VR41_CONF_CS (_ULCAST_(1) << 12)
#define VR41_CONF_M16 (_ULCAST_(1) << 20)
#define VR41_CONF_AD (_ULCAST_(1) << 23)
/* Bits specific to the R30xx. */
#define R30XX_CONF_FDM (_ULCAST_(1) << 19)
#define R30XX_CONF_REV (_ULCAST_(1) << 22)
#define R30XX_CONF_AC (_ULCAST_(1) << 23)
#define R30XX_CONF_RF (_ULCAST_(1) << 24)
#define R30XX_CONF_HALT (_ULCAST_(1) << 25)
#define R30XX_CONF_FPINT (_ULCAST_(7) << 26)
#define R30XX_CONF_DBR (_ULCAST_(1) << 29)
#define R30XX_CONF_SB (_ULCAST_(1) << 30)
#define R30XX_CONF_LOCK (_ULCAST_(1) << 31)
/* Bits specific to the TX49. */
#define TX49_CONF_DC (_ULCAST_(1) << 16)
#define TX49_CONF_IC (_ULCAST_(1) << 17) /* conflict with CONF_SC */
#define TX49_CONF_HALT (_ULCAST_(1) << 18)
#define TX49_CONF_CWFON (_ULCAST_(1) << 27)
/* Bits specific to the MIPS32/64 PRA. */
#define MIPS_CONF_MT (_ULCAST_(7) << 7)
#define MIPS_CONF_AR (_ULCAST_(7) << 10)
#define MIPS_CONF_AT (_ULCAST_(3) << 13)
#define MIPS_CONF_M (_ULCAST_(1) << 31)
/*
* Bits in the MIPS32/64 PRA coprocessor 0 config registers 1 and above.
*/
#define MIPS_CONF1_FP (_ULCAST_(1) << 0)
#define MIPS_CONF1_EP (_ULCAST_(1) << 1)
#define MIPS_CONF1_CA (_ULCAST_(1) << 2)
#define MIPS_CONF1_WR (_ULCAST_(1) << 3)
#define MIPS_CONF1_PC (_ULCAST_(1) << 4)
#define MIPS_CONF1_MD (_ULCAST_(1) << 5)
#define MIPS_CONF1_C2 (_ULCAST_(1) << 6)
#define MIPS_CONF1_DA (_ULCAST_(7) << 7)
#define MIPS_CONF1_DL (_ULCAST_(7) << 10)
#define MIPS_CONF1_DS (_ULCAST_(7) << 13)
#define MIPS_CONF1_IA (_ULCAST_(7) << 16)
#define MIPS_CONF1_IL (_ULCAST_(7) << 19)
#define MIPS_CONF1_IS (_ULCAST_(7) << 22)
#define MIPS_CONF1_TLBS (_ULCAST_(63)<< 25)
#define MIPS_CONF2_SA (_ULCAST_(15)<< 0)
#define MIPS_CONF2_SL (_ULCAST_(15)<< 4)
#define MIPS_CONF2_SS (_ULCAST_(15)<< 8)
#define MIPS_CONF2_SU (_ULCAST_(15)<< 12)
#define MIPS_CONF2_TA (_ULCAST_(15)<< 16)
#define MIPS_CONF2_TL (_ULCAST_(15)<< 20)
#define MIPS_CONF2_TS (_ULCAST_(15)<< 24)
#define MIPS_CONF2_TU (_ULCAST_(7) << 28)
#define MIPS_CONF3_TL (_ULCAST_(1) << 0)
#define MIPS_CONF3_SM (_ULCAST_(1) << 1)
#define MIPS_CONF3_MT (_ULCAST_(1) << 2)
#define MIPS_CONF3_SP (_ULCAST_(1) << 4)
#define MIPS_CONF3_VINT (_ULCAST_(1) << 5)
#define MIPS_CONF3_VEIC (_ULCAST_(1) << 6)
#define MIPS_CONF3_LPA (_ULCAST_(1) << 7)
#define MIPS_CONF3_DSP (_ULCAST_(1) << 10)
/*
* Bits in the MIPS32/64 coprocessor 1 (FPU) revision register.
*/
#define MIPS_FPIR_S (_ULCAST_(1) << 16)
#define MIPS_FPIR_D (_ULCAST_(1) << 17)
#define MIPS_FPIR_PS (_ULCAST_(1) << 18)
#define MIPS_FPIR_3D (_ULCAST_(1) << 19)
#define MIPS_FPIR_W (_ULCAST_(1) << 20)
#define MIPS_FPIR_L (_ULCAST_(1) << 21)
#define MIPS_FPIR_F64 (_ULCAST_(1) << 22)
/*
* R10000 performance counter definitions.
*
* FIXME: The R10000 performance counter opens a nice way to implement CPU
* time accounting with a precission of one cycle. I don't have
* R10000 silicon but just a manual, so ...
*/
/*
* Events counted by counter #0
*/
#define CE0_CYCLES 0
#define CE0_INSN_ISSUED 1
#define CE0_LPSC_ISSUED 2
#define CE0_S_ISSUED 3
#define CE0_SC_ISSUED 4
#define CE0_SC_FAILED 5
#define CE0_BRANCH_DECODED 6
#define CE0_QW_WB_SECONDARY 7
#define CE0_CORRECTED_ECC_ERRORS 8
#define CE0_ICACHE_MISSES 9
#define CE0_SCACHE_I_MISSES 10
#define CE0_SCACHE_I_WAY_MISSPREDICTED 11
#define CE0_EXT_INTERVENTIONS_REQ 12
#define CE0_EXT_INVALIDATE_REQ 13
#define CE0_VIRTUAL_COHERENCY_COND 14
#define CE0_INSN_GRADUATED 15
/*
* Events counted by counter #1
*/
#define CE1_CYCLES 0
#define CE1_INSN_GRADUATED 1
#define CE1_LPSC_GRADUATED 2
#define CE1_S_GRADUATED 3
#define CE1_SC_GRADUATED 4
#define CE1_FP_INSN_GRADUATED 5
#define CE1_QW_WB_PRIMARY 6
#define CE1_TLB_REFILL 7
#define CE1_BRANCH_MISSPREDICTED 8
#define CE1_DCACHE_MISS 9
#define CE1_SCACHE_D_MISSES 10
#define CE1_SCACHE_D_WAY_MISSPREDICTED 11
#define CE1_EXT_INTERVENTION_HITS 12
#define CE1_EXT_INVALIDATE_REQ 13
#define CE1_SP_HINT_TO_CEXCL_SC_BLOCKS 14
#define CE1_SP_HINT_TO_SHARED_SC_BLOCKS 15
/*
* These flags define in which privilege mode the counters count events
*/
#define CEB_USER 8 /* Count events in user mode, EXL = ERL = 0 */
#define CEB_SUPERVISOR 4 /* Count events in supvervisor mode EXL = ERL = 0 */
#define CEB_KERNEL 2 /* Count events in kernel mode EXL = ERL = 0 */
#define CEB_EXL 1 /* Count events with EXL = 1, ERL = 0 */
#ifndef __ASSEMBLY__
/*
* Macros to access the system control coprocessor
*/
#define __read_32bit_c0_register(source, sel) \
({ int __res; \
if (sel == 0) \
__asm__ __volatile__( \
"mfc0\t%0, " #source "\n\t" \
: "=r" (__res)); \
else \
__asm__ __volatile__( \
".set\tmips32\n\t" \
"mfc0\t%0, " #source ", " #sel "\n\t" \
".set\tmips0\n\t" \
: "=r" (__res)); \
__res; \
})
#define __write_32bit_c0_register(register, sel, value) \
do { \
if (sel == 0) \
__asm__ __volatile__( \
"mtc0\t%z0, " #register "\n\t" \
: : "Jr" ((unsigned int)(value))); \
else \
__asm__ __volatile__( \
".set\tmips32\n\t" \
"mtc0\t%z0, " #register ", " #sel "\n\t" \
".set\tmips0" \
: : "Jr" ((unsigned int)(value))); \
} while (0)
#define read_c0_index() __read_32bit_c0_register($0, 0)
#define write_c0_index(val) __write_32bit_c0_register($0, 0, val)
#define read_c0_random() __read_32bit_c0_register($1, 0)
#define write_c0_random(val) __write_32bit_c0_register($1, 0, val)
#define read_c0_entrylo0() __read_32bit_c0_register($2, 0)
#define write_c0_entrylo0(val) __write_32bit_c0_register($2, 0, val)
#define read_c0_entrylo1() __read_32bit_c0_register($3, 0)
#define write_c0_entrylo1(val) __write_32bit_c0_register($3, 0, val)
#define read_c0_conf() __read_32bit_c0_register($3, 0)
#define write_c0_conf(val) __write_32bit_c0_register($3, 0, val)
#define read_c0_context() __read_32bit_c0_register($4, 0)
#define write_c0_context(val) __write_32bit_c0_register($4, 0, val)
#define read_c0_userlocal() __read_32bit_c0_register($4, 2)
#define write_c0_userlocal(val) __write_32bit_c0_register($4, 2, val)
#define read_c0_pagemask() __read_32bit_c0_register($5, 0)
#define write_c0_pagemask(val) __write_32bit_c0_register($5, 0, val)
#define read_c0_wired() __read_32bit_c0_register($6, 0)
#define write_c0_wired(val) __write_32bit_c0_register($6, 0, val)
#define read_c0_info() __read_32bit_c0_register($7, 0)
#define read_c0_cache() __read_32bit_c0_register($7, 0) /* TX39xx */
#define write_c0_cache(val) __write_32bit_c0_register($7, 0, val)
#define read_c0_badvaddr() __read_32bit_c0_register($8, 0)
#define write_c0_badvaddr(val) __write_32bit_c0_register($8, 0, val)
#define read_c0_count() __read_32bit_c0_register($9, 0)
#define write_c0_count(val) __write_32bit_c0_register($9, 0, val)
#define read_c0_count2() __read_32bit_c0_register($9, 6) /* pnx8550 */
#define write_c0_count2(val) __write_32bit_c0_register($9, 6, val)
#define read_c0_count3() __read_32bit_c0_register($9, 7) /* pnx8550 */
#define write_c0_count3(val) __write_32bit_c0_register($9, 7, val)
#define read_c0_entryhi() __read_32bit_c0_register($10, 0)
#define write_c0_entryhi(val) __write_32bit_c0_register($10, 0, val)
#define read_c0_compare() __read_32bit_c0_register($11, 0)
#define write_c0_compare(val) __write_32bit_c0_register($11, 0, val)
#define read_c0_compare2() __read_32bit_c0_register($11, 6) /* pnx8550 */
#define write_c0_compare2(val) __write_32bit_c0_register($11, 6, val)
#define read_c0_compare3() __read_32bit_c0_register($11, 7) /* pnx8550 */
#define write_c0_compare3(val) __write_32bit_c0_register($11, 7, val)
#define read_c0_status() __read_32bit_c0_register($12, 0)
#define write_c0_status(val) __write_32bit_c0_register($12, 0, val)
#define read_c0_cause() __read_32bit_c0_register($13, 0)
#define write_c0_cause(val) __write_32bit_c0_register($13, 0, val)
#define read_c0_epc() __read_32bit_c0_register($14, 0)
#define write_c0_epc(val) __write_32bit_c0_register($14, 0, val)
#define read_c0_prid() __read_32bit_c0_register($15, 0)
#define read_c0_ebase() __read_32bit_c0_register($15, 1)
#define write_c0_ebase(val) __write_32bit_c0_register($15, 1, val)
#define read_c0_config() __read_32bit_c0_register($16, 0)
#define read_c0_config1() __read_32bit_c0_register($16, 1)
#define read_c0_config2() __read_32bit_c0_register($16, 2)
#define read_c0_config3() __read_32bit_c0_register($16, 3)
#define write_c0_config(val) __write_32bit_c0_register($16, 0, val)
#define write_c0_config1(val) __write_32bit_c0_register($16, 1, val)
#define write_c0_config2(val) __write_32bit_c0_register($16, 2, val)
#define write_c0_config3(val) __write_32bit_c0_register($16, 3, val)
/*
* Macros to access the floating point coprocessor control registers
*/
#define read_32bit_cp1_register(source) \
({ int __res; \
__asm__ __volatile__( \
".set\tpush\n\t" \
".set\treorder\n\t" \
/* gas fails to assemble cfc1 for some archs (octeon).*/ \
".set\tmips1\n\t" \
"cfc1\t%0,"STR(source)"\n\t" \
".set\tpop" \
: "=r" (__res)); \
__res;})
#define write_32bit_cp1_register(register, value) \
do { \
__asm__ __volatile__( \
"ctc1\t%z0, "STR(register)"\n\t" \
: : "Jr" ((unsigned int)(value))); \
} while (0)
#define read_c1_status() read_32bit_cp1_register(CP1_STATUS)
#define read_c1_revision() read_32bit_cp1_register(CP1_REVISION);
#define write_c1_status(val) write_32bit_cp1_register(CP1_STATUS, val)
#endif /* end of __ASSEMBLY__ */
#endif /* end of __MIPSREGS_H__ */
test_fpu.h
// 硬浮点测试用例的头文件
#ifndef __OPENLOONGSON_TEST_FPU_H
#define __OPENLOONGSON_TEST_FPU_H
// 测试使用硬浮点进行浮点数的加减乘除
void test_fpu(void);
#endif
test_fpu.c
// 硬浮点测试用例的源文件
#include "../lib/ls1c_public.h"
// 每个测试用例中for循环的最大值
#define TEST_FPU_MAX_COUNT (1000)
// 使用硬浮点执行浮点数的加法
void test_fpu_add(void)
{
unsigned int i = 0;
float sum_f = 0.0;
unsigned int *sum_p = (unsigned int *)&sum_f;
myprintf("\n\n----------------------%s-------------------\n", __FUNCTION__);
for (i=0; i
测试FPU是否移植成功的测试用例中，分别执行1000次浮点数的加、减、乘和除。测试时将浮点数所占的4个字节打印出来了。可以另外在linux下用龙芯1c执行一篇这个测试函数，然后对比查看打印结果是否一致，来判断浮点运算是否正确。
1c库gitee上最新的代码已经可以使用printf的%f来打印浮点数了。
另外，这里也只测试了单精度浮点。
感谢耐心看完！